- John L. Hennessy Co.2
- John M. Russell, Inc.3
- Joint Board, Fur, Leather, and Machine Workers' Unions2
- Jonas Construction Co., Inc.2
- Jonas Equities, Inc.2
- Jonas, Max1
- Jonat Co.18
- Jonat Realty Corp.1
- Jonathan Woodner Co.14
- Jones Lang Wootton1
- Jones Lang Wootton International Real Estate Consultants1
- Jonic Properties1
- Joselow, Abraham1
- Joseph H. Lopin and Co.1
- Joseph H. Nassoit Management Corp.15
- Joseph H. Nassoit, Inc.11
- Joseph P. Blitz, Inc.3
- Julien J. Studley, Inc.25
- Julius S. Brauman and Son1
- Julius Tishman and Sons, Inc.1
- Junard Organization1
- Juncker, J. Jacques1
- Juster Construction Corp.1
- Juster, M.W.1
- K and H Associates1
- K. Equities Inc.1
- K.I. Realty Corp.1
- KBS Construction16
- Kalb Construction Corp.1
- Kalikow Construction Corp.24
- Kalikow Management1
- Kalikow Properties, Inc.2
- Kalikow Realty and Construction Corp.5
- Kalikow, Joseph1
- Kaliman Brothers21
- Kalt, Max1
- Kanam Building Corp.1
- Kapson Building Corp.1
- Karp Construction Corp.1
- Kaskel, Alfred L.16
- Kaskel, Arthur L.5
- Kaswick Reaty Corp.1
- Katzen Realty1
- Kaufman, Melvin1
- Kaufman, William8
- Kavner Holding Corp.1
- Kaybar Apartments, Inc.1
- Kaye Realty Co.1
- Kaye and Sons, Inc1
- Kaye and Sons, Inc.4
- Kaye-Abramson Realty and Construction Co.1
- Kebel Associates1
- Kehaya Realty Corp.2
- Keith House, Inc.1
- Kelbert Realty Corp.1
- Kellner Gardens, Inc.1
- Kellner and Anchell1
- Kellner and Kellner, Inc.1
- Kellner and Liningston1
- Kellner, Gustave10