The 340 was conceived of as a cabin-class development of the successful Cessna 310.
The 340 is a six-seat aircraft, with four passenger seats, an aisle and an airstair door. The tail and landing gear were based on the Cessna 310's units, while its wings were from the Cessna 414. The 340's primary selling feature was its spacious, pressurized cabin, the first in a light twin.
Work on the 340 began in 1969 and the first aircraft was delivered in 1971, behind schedule as one of the prototypes crashed during flight testing in 1970.
The early models have two turbocharged Continental TSIO-520-K engines with 285 hp (214 kW) each. Starting in 1976 the engines were upgraded to the more powerful Continental TSIO-520-NB engines of 310 hp (233 kW). This variant is known as the 340A and it also features smaller 75.5-inch (1,920 mm) diameter propellers to reduce noise and meet ICAO Annex 16 noise requirements.
The Cessna 335 was marketed as a low-priced, non-pressurized, version powered by 300 hp (225 kW) Continental TSIO-520-EB engines. The prototype 335 made its maiden flight on December 5, 1978, with the first production aircraft flying in 1979. It was not a market success, with only 64 built by the time production ended in 1980. The 340 was more successful and remained in production until 1984 with 1287 built.