- J.C. and M.G. Mayer1
- J.D. Robilotto Co., Inc.2
- J.E. Watson, Inc.1
- J.F. Cahill and Co., Inc.2
- J.G. Haft and Co., Inc.12
- J.G. MacInnis Co.2
- J.H. Taylor Construction Co., Inc.4
- J.H. Taylor Management Co., Inc.10
- J.I. Sopher and Co., Inc.34
- Jack Resnick and Son11
- Jaffe, Sheldon A.1
- James D. Landauer Associates, Inc.1
- James Felt and Co., Inc.2
- James Felt-Huberth and Huberth, Inc.1
- James N. Wells' Sons, Inc.10
- James Stewart and Co., Inc.2
- Janos-Langer6
- Jay R. Braus Co.4
- John Avlon Real Estate1
- John Avlon, Inc.35
- John H. Carpenter Jr., Inc.5
- John J. Reynolds Management Co., Inc.2
- Jonat Co.18
- Jonathan Woodner Co.11
- Jones Lang Wootton1
- Jones Lang Wootton International Real Estate Consultants1
- Jonic Properties1
- Joseph H. Nassoit Management Corp.15
- Joseph H. Nassoit, Inc.11
- Joseph P. Blitz, Inc.3
- Julien J. Studley, Inc.25
- Julius Tishman and Sons, Inc.1
- Juncker, J. Jacques1
- Juster Construction Corp.1
- K. Equities Inc.1
- Kalikow Construction Corp.16
- Kalikow Properties, Inc.1
- Kalikow Realty and Construction Corp.5
- Kaliman Brothers21
- Kaswick Reaty Corp.1
- Katzen Realty1
- Kaufman, William8
- Kehaya Realty Corp.2
- Kelbert Realty Corp.1
- Kellner and Liningston1
- Kenneth McCrary Associates, Inc.2
- Kensington Estates Inc.1
- Keoppel and Keoppel8
- Kessler Wohl Associates7
- Kimmel Brothers Realty and Construction Co.3
- Kleban and Leader1
- Klein, Frederick8
- Klein, Murray2
- Knight Realty1
- Kramer, Louis1
- Kratter Corp.1
- Kraus, David1
- Kreisel Co.1
- L-V Realty Corp.1
- L.J. Phillips and Co.5