The Swiss FFA P-16 jet fighter, cancelled by the federal government in the late 1950s, caught the attention of Bill Lear Snr, who saw in it the basis for a twin-jet executive aircraft. He initiated preliminary design work at St Gallen, Switzerland, in November 1959 and sold his electronics company to the Siegler Corporation. Lear then formed the Swiss American Aviation Corporation to develop the aircraft, known originally as the SAAC Lear Jet 23. An important objective was to keep the aircraft's gross weight below 5670kg so that it would qualify for single-pilot operation under FAA CAR.3 regulations and for air taxi operations without requiring CAB approval.

In August 1962, after the design had been finalised and tooling was in progress, Lear transferred the project to Wichita, Kansas, and renamed the organisation the Lear Jet Corporation. In every way a stylish aircraft reflecting its fighter origins, the Learjet 23 marked a new era in 'bizjet' design, offering very high performance - if not much headroom.

The prototype made its first flight on 7 October 1963, the second and third aircraft being flown on 5 March and 15 May 1964 respectively. Following the receipt of certification on 31 July the first production Lear Jet 23 was delivered on 13 October 1964 to the Chemical and Industrial Corporation of Cincinnati, Ohio. Despite the fact that the Lear Jet was considerably smaller than the piston-engined aircraft that it was designed to replace, it more than made up for this in performance, and though intended for single-pilot operation the basic layout was for a crew of two and for five to seven passengers. The first 30 production aircraft to be completed were powered by 1293kg thrust General Electric CJ610-1 turbojets, but the remainder of the production run of a little over 100 Lear Jet 23s had CJ610-4s of similar thrust.