The airport was built in 1929 and dedicated on July 6, 1930, one of 25 such projects in U.S. cities by the newly incorporated airplane manufacturer Curtiss-Wright. The airport was originally known as Curtiss-Wright Field, hence the letters "WC" in its airport codes. In 1945, Curtiss-Wright sold it to Fliteways, Inc., the airport's property manager since 1936. Milwaukee County purchased the airport from Fliteways in July 1947, when it was 131 acres (53 ha) in size. It was host to the Experimental Aircraft Association's earliest Fly-In Conventions from 1953 to 1958. The airport was renamed in July 1959 for Lawrence J. Timmerman (1878–1959), chairman of the Milwaukee County Board of Supervisors from 1936 to 1959.
Lawrence J. Timmerman Airport currently serves various general aviation groups. The current fixed base operator is Gran Aire. The airport is home to the Milwaukee chapter of Youth and Aviation, as well as two Civil Air Patrol squadrons; the Timmerman Composite Squadron, and Milwaukee Senior Support Squadron 10. The airport also serves many private and public users.
Lawrence J. Timmerman Airport covers an area of 420 acres (170 ha) which contains two asphalt paved runways: 4L/22R measuring 3,202 x 75 ft (976 x 23 m) and 15L/33R measuring 4,106 x 75 ft (1,252 x 23 m). It also has two turf runways: 4R/22L measuring 2,862 x 275 ft (872 x 84 m) and 15R/33L measuring 3,251 x 275 ft (991 x 84 m).
For the 12-month period ending December 31, 2004, the airport had 69,134 aircraft operations, an average of 189 per day: 99% general aviation, 1% air taxi and <1% military. There are 104 aircraft based at this airport: 74% single-engine, 21% multi-engine, 3% jet and 2% helicopter.