Jaromír Krejcar (25 July 1895, Hundsheim, Austria – 5 October 1950, London) was a Czech functionalistic architect, student of Jan Kotěra and member of Devětsil.

He collaborated with Czech structural engineer, Dr. Jaroslav Joseph Polivka on the internationally acclaimed Czech Pavilion at the Paris Exposition of 1937.

Krejcar was husband of journalist Milena Jesenská and father of Jana Krejcarová. After the communist coup in 1948 he went to exile to the United Kingdom.