| Union High School | Union | High | 09-12 | 2,308 | · |
| Plainfield High School | Plainfield | High | 09-12 | 1,925 | · |
| Westfield Senior High School | Westfield | High | 09-12 | 1,818 | · |
| Linden High School | Linden | High | 09-12 | 1,801 | · |
| Scotch Plains-Fanwood High School | Scotch Plains | High | 09-12 | 1,510 | · |
| John E. Dwyer Technology Academy | Elizabeth | High | 09-12 | 1,443 | · |
| College Achieve Central Charter School | Plainfield | Other | KG-12 | 1,403 | · |
| Admiral William F. Halsey Jr. Health & Public Safety Academy | Elizabeth | High | 09-12 | 1,299 | · |
| Elizabeth High School - Frank J Cicarell Academy | Elizabeth | High | 09-12 | 1,281 | · |
| Rahway High School | Rahway | High | 09-12 | 1,204 | · |
| Summit High School | Summit | High | 09-12 | 1,161 | · |
| Terence C. Reilly School No 7 | Elizabeth | Middle | 02-08 | 1,126 | · |
| Cranford High School | Cranford | High | 09-12 | 1,095 | · |
| William F. Halloran School No.22 | Elizabeth | Middle | 02-08 | 1,089 | · |
| Thomas Jefferson Arts Academy | Elizabeth | High | 09-12 | 1,070 | · |
| Toussaint Louverture-Marquis de Lafayette School No. 6 | Elizabeth | Elementary | PK-08 | 1,042 | · |
| Alexander Hamilton Preparatory Academy | Elizabeth | High | 09-12 | 996 | · |
| Burnet Middle School | Union | Middle | 05-08 | 981 | · |
| Lawton C. Johnson Summit Middle School | Summit | Middle | 06-08 | 942 | · |
| Governor Livingston High School | Berkeley Heights | High | 09-12 | 936 | · |
| Hillside High School | Hillside | High | 09-12 | 925 | · |
| Malcolm E Nettingham Middle School | Scotch Plains | Middle | 05-08 | 917 | · |
| Juan Pablo Duarte - Jose Julian Marti School No 28 | Elizabeth | Elementary | PK-08 | 915 | · |
| Jerome Dunn Academy No 9 | Elizabeth | Elementary | KG-08 | 896 | · |
| Dr. Antonia Pantoja School No. 27 | Elizabeth | Elementary | PK-08 | 885 | · |
| Abraham Clark High School | Roselle | High | 09-12 | 884 | · |
| Abraham Lincoln School No. 14 | Elizabeth | Elementary | KG-08 | 840 | · |
| Terrill Middle School | Scotch Plains | Middle | 05-08 | 837 | · |
| Maxson Middle School | Plainfield | Middle | 06-08 | 818 | · |
| Thomas A. Edison Career and Technical Academy | Elizabeth | High | 09-12 | 810 | · |
| Nicholas S. Lacorte-Peterstown School No. 3 | Elizabeth | Elementary | KG-08 | 807 | · |
| Dr. Albert Einstein Academy School No. 29 | Elizabeth | Elementary | PK-08 | 799 | · |
| Mabel G. Homes School No. 5 | Elizabeth | Elementary | PK-08 | 799 | · |
| Joseph Battin School No 4 | Elizabeth | Elementary | PK-08 | 783 | · |
| Thomas Edison Intermediate School | Westfield | Middle | 06-08 | 781 | · |
| Hannah Caldwell Elementary | Union | Elementary | PK-04 | 779 | · |
| Hubbard Middle School | Plainfield | Middle | 06-08 | 775 | · |
| David Brearley Middle/High School | Kenilworth | High | 07-12 | 774 | · |
| Orange Avenue School | Cranford | Middle | 03-08 | 765 | · |
| Chessie Dentley Roberts Academy School No. 30 | Elizabeth | Elementary | PK-08 | 764 | · |
| Hillside Avenue School | Cranford | Elementary | KG-08 | 734 | · |
| Arthur L. Johnson High School | Clark | High | 09-12 | 731 | · |
| Kawameeh Middle School | Union | Middle | 05-08 | 710 | · |
| Dr. Orlando Edreira Academy School No. 26 | Elizabeth | Elementary | PK-08 | 694 | · |
| Myles J. McManus MIddle School | Linden | Middle | 06-08 | 686 | · |
| Warren G. Harding Elementary School | Kenilworth | Elementary | PK-06 | 681 | · |
| Allen W. Roberts School | New Providence | Elementary | PK-06 | 676 | · |
| Rahway 7th & 8th Grade Academy | Rahway | Middle | 07-08 | 675 | · |
| Christopher Columbus School No. 15 | Elizabeth | Elementary | KG-08 | 666 | · |
| New Providence High School | New Providence | High | 09-12 | 666 | · |
| Joseph E. Soehl Middle School | Linden | Middle | 06-08 | 662 | · |
| Jonathan Dayton High School | Springfield | High | 09-12 | 659 | · |
| Roosevelt Intermediate School | Westfield | Middle | 06-08 | 658 | · |
| Abram P. Morris Early Childhood Center | Hillside | Elementary | PK-01 | 650 | · |
| Washington Community School | Plainfield | Elementary | PK-05 | 649 | · |
| Elmora School No. 12 | Elizabeth | Elementary | PK-08 | 648 | · |
| Madison Monroe School No. 16 | Elizabeth | Elementary | PK-08 | 637 | · |
| Winfield Scott School No. 2 | Elizabeth | Elementary | PK-08 | 637 | · |
| Roselle Park High School | Roselle Park | High | 09-12 | 630 | · |
| Franklin Elementary School | Rahway | Elementary | PK-06 | 627 | · |
| Cedarbrook Elementary School | Plainfield | Elementary | KG-08 | 623 | · |
| Victor Mravlag School No. 21 | Elizabeth | Elementary | PK-08 | 623 | · |
| Salt Brook School | New Providence | Elementary | KG-06 | 607 | · |
| Sonia Sotomayor School No 25 | Elizabeth | Elementary | KG-08 | 604 | · |
| Evergreen Elementary School | Plainfield | Elementary | KG-05 | 602 | · |
| Nicholas Murray Butler Academy School No. 23 | Elizabeth | Elementary | KG-08 | 600 | · |
| Number 2 | Linden | Elementary | PK-05 | 584 | · |
| Frank K. Hehnly | Clark | Elementary | KG-05 | 576 | · |
| Roosevelt Elementary School | Rahway | Elementary | PK-06 | 573 | · |
| Washington Elementary | Union | Elementary | PK-04 | 572 | · |
| Woodrow Wilson School No. 19 | Elizabeth | Elementary | PK-08 | 571 | · |
| Columbia Middle School | Berkeley Hts | Middle | 06-08 | 560 | · |
| George Washington Academy School No. 1 | Elizabeth | Elementary | PK-08 | 554 | · |
| Edward V. Walton Primary School | Springfield | Elementary | PK-02 | 551 | · |
| J. Ackerman Coles Elementary School | Scotch Plains | Elementary | PK-04 | 535 | · |
| Cresthaven Academy Charter School | Plainfield | Elementary | KG-06 | 532 | · |
| Franklin Elementary School | Westfield | Elementary | 01-05 | 532 | · |
| Jefferson Elementary | Union | Middle | 05-05 | 528 | · |
| William J. McGinn Elementary School | Scotch Plains | Elementary | KG-04 | 527 | · |
| Florence M. Gaudineer Middle School | Springfield | Middle | 06-08 | 518 | · |
| Carl H. Kumpf School | Clark | Middle | 06-08 | 516 | · |
| Union County Tech | Scotch Plains | High | 09-12 | 511 | · |
| Emerson Community School | Plainfield | Elementary | KG-05 | 509 | · |
| Robert Morris School No. 18 | Elizabeth | Elementary | KG-08 | 506 | · |
| Roselle Park Middle School | Roselle Park | Middle | 06-08 | 479 | · |
| Grover Cleveland Elementary School | Rahway | Elementary | PK-06 | 469 | · |
| Deerfield Elementary School | Mountainside | Middle | 03-08 | 467 | · |
| Jefferson Elementary School | Westfield | Elementary | 01-05 | 466 | · |
| Livingston Elementary | Union | Elementary | PK-04 | 465 | · |
| John Marshal School No. 20 | Elizabeth | Elementary | KG-08 | 454 | · |
| Franklin Elementary | Union | Elementary | PK-04 | 452 | · |
| Jefferson Elementary School | Plainfield | Elementary | PK-05 | 441 | · |
| Number 4 | Linden | Elementary | PK-05 | 437 | · |
| Leonard V Moore Middle School | Roselle | Middle | 05-06 | 436 | · |
| Grace Wilday Junior High School | Roselle | Middle | 07-08 | 435 | · |
| Benjamin Franklin School No. 13 | Elizabeth | Elementary | KG-08 | 434 | · |
| K. Johnson D. Vaughan and M. Jackson STEM Academy | Elizabeth | High | 09-12 | 427 | · |
| Howard B. Brunner Elementary School | Scotch Plains | Elementary | PK-04 | 425 | · |
| Connecticut Farms Elementary | Union | Elementary | PK-05 | 420 | · |
| Dewitt D. Barlow Elementary School | Plainfield | Elementary | KG-05 | 417 | · |
| iPrep Academy School No 8 | Elizabeth | Elementary | KG-08 | 416 | · |
| Tamaques Elementary School | Westfield | Elementary | 01-05 | 414 | · |
| Clinton Elementary School | Plainfield | Elementary | PK-05 | 413 | · |
| School One Elementary | Scotch Plains | Elementary | PK-04 | 406 | · |
| Evergreen Elementary School | Scotch Plains | Elementary | PK-04 | 405 | · |
| The Queen City Academy Charter School | Plainfield | Other | KG-12 | 403 | · |
| New Providence Middle School | New Providence | Middle | 07-08 | 398 | · |
| Valley Road School | Clark | Elementary | KG-05 | 395 | · |
| Frederic W. Cook Elementary School | Plainfield | Elementary | KG-05 | 389 | · |
| Madison Elementary School | Rahway | Elementary | PK-06 | 387 | · |
| Battle Hill Elementary | Union | Elementary | PK-04 | 385 | · |
| Ola Edwards Community School | Hillside | Elementary | 02-06 | 381 | · |
| Hurden Looker School | Hillside | Elementary | 02-06 | 376 | · |
| Walter O. Krumbiegel Middle School | Hillside | Middle | 07-08 | 376 | · |
| Number 1 | Linden | Elementary | PK-05 | 374 | · |
| Lincoln | Garwood | Elementary | PK-08 | 357 | · |
| Plainfield Academy For The Arts & Advanced Studies | Plainfield | High | 07-12 | 356 | · |
| Brookside Place School | Cranford | Elementary | KG-05 | 355 | · |
| Charles H. Stillman Elementary School | Plainfield | Elementary | KG-04 | 354 | · |
| Sherman Elementary School | Roselle Park | Elementary | PK-05 | 353 | · |
| Wilson Elementary School | Westfield | Elementary | 01-05 | 345 | · |
| J. Christian Bollwage Finance Academy | Elizabeth | High | 09-12 | 342 | · |
| Washington Elementary School | Roselle | Elementary | 01-04 | 337 | · |
| Union County TEAMS Charter School | Plainfield | Other | KG-12 | 334 | · |
| McKinley Elementary School | Westfield | Elementary | 01-05 | 332 | · |
| Number 6 | Linden | Elementary | PK-05 | 332 | · |
| Lincoln-Hubbard Elementary School | Summit | Elementary | 01-05 | 328 | · |
| Franklin Elementary School | Summit | Elementary | 01-05 | 327 | · |
| Number 9 | Linden | Elementary | PK-05 | 324 | · |
| Donald Stewart Early Childhood Center No 51 | Elizabeth | Prekindergarten | PK-PK | 310 | · |
| Washington Elementary School | Summit | Elementary | 01-05 | 310 | · |
| Robert Gordon Elementary School | Roselle Park | Elementary | PK-05 | 308 | · |
| Dr. Martin Luther King Jr. Early Childhood Center No 52 | Elizabeth | Prekindergarten | PK-PK | 307 | · |
| Harrison Elementary School | Roselle | Elementary | 01-04 | 305 | · |
| Brayton Elementary School | Summit | Elementary | 01-05 | 304 | · |
| Frances C. Smith Early Childhood Center No 50 | Elizabeth | Prekindergarten | PK-PK | 304 | · |
| Academy For Allied Health Sciences | Scotch Plains | High | 09-12 | 303 | · |
| Union County Magnet High School | Scotch Plains | High | 09-12 | 303 | · |
| Dr. Charles C. Polk School | Roselle | Elementary | 01-04 | 301 | · |
| Number 8 | Linden | Elementary | PK-05 | 300 | · |
| Academy For Information Technology | Scotch Plains | High | 09-12 | 297 | · |
| Walnut Avenue School | Cranford | Elementary | PK-02 | 294 | · |
| Number 5 | Linden | Elementary | PK-05 | 290 | · |
| Lincoln Early Childhood Center | Westfield | Elementary | PK-KG | 282 | · |
| Thomas P. Hughes School | Berkeley Hts | Elementary | 03-05 | 276 | · |
| Beechwood School | Mountainside | Elementary | PK-02 | 269 | · |
| Washington Elementary School | Westfield | Elementary | 01-05 | 263 | · |
| Ernest J. Finizio Jr. - Aldene School | Roselle Park | Elementary | PK-05 | 261 | · |
| The Barack Obama Green Charter High School | Plainfield | High | 06-12 | 257 | · |
| Livingston Avenue School | Cranford | Elementary | 03-05 | 253 | · |
| Thelma L. Sandmeier Elementary School | Springfield | Elementary | 03-05 | 245 | · |
| Number 10 | Linden | Elementary | PK-05 | 242 | · |
| Mary Kay McMillin Early Childhood Center | Berkeley Heights | Elementary | PK-02 | 241 | · |
| William Woodruff School | Berkeley Hts | Elementary | KG-02 | 234 | · |
| Bloomingdale Avenue School | Cranford | Elementary | KG-02 | 233 | · |
| Academy For Performing Arts | Scotch Plains | High | 09-12 | 231 | · |
| Mountain Park School | Berkeley Hts | Elementary | 03-05 | 223 | · |
| James Caldwell Elementary School | Springfield | Elementary | 03-05 | 219 | · |
| Jefferson Elementary School | Summit | Elementary | 01-05 | 215 | · |
| Deanna G. Taylor Academy | Hillside | Elementary | 02-06 | 211 | · |
| Primary Center at Wilson | Summit | Elementary | PK-KG | 202 | · |
| Kindergarten Success Academy | Roselle | Elementary | KG-KG | 200 | · |
| Primary Center at Jefferson | Summit | Elementary | PK-KG | 143 | · |
| Winfield Township | Winfield | Elementary | PK-08 | 135 | · |
| Hillside Innovation Academy | Hillside | Middle | 07-08 | 99 | · |
| Hillcrest Academy-North | Scotch Plains | High | 09-12 | 81 | · |
| Developmental Learning Center New Providence | New Providence | Other | KG-09 | 74 | · |
| Hillcrest Academy-South | Westfield | High | 09-12 | 69 | · |
| Pinnacle Academy High School | Plainfield | High | 09-12 | 60 | · |
| Westlake | Westfield | Other | 04-12 | 52 | · |
| Crossroads School | Westfield | Elementary | PK-08 | 49 | · |
| Lamberts Mill Academy | Westfield | High | 06-12 | 36 | · |
| Work Readiness Academy | Westfield | High | 12-12 | 25 | · |
| Simon Youth Academy | Elizabeth | High | 09-12 | 23 | · |
| Clark Preschool Annex | Clark | Prekindergarten | PK-PK | 21 | · |
| Union County Career & Technical Institute | Scotch Plains | High | 09-12 | 17 | · |
| Raymond J. Lesniak Experience Strength & Hope Recovery HS | Roselle | High | 09-12 | 2 | · |
| UNION REGIONAL SCHOOL | Scotch Plains | Other | 01-12 | 0 | · |