First flown in August 1929 the LéO 21 was a twin-engined biplane airliner with a fixed tailskid landing gear. It retained the basic structure of the LéO 20 night bomber but with a new wider fuselage. It had room for six passengers in a nose cabin and a further 12 passengers in the main cabin with an open cockpit for the pilot.
The second LéO 21 was fitted with two 450 hp (336 kW) Renault 12Ja engines and re-designated as a LéO 212. It was converted by the Wagons-Lits company as a dining aircraft. The first LéO 21 became an avion-bar in 1929 and was re-designated LéO 211; it was later modified in 1931 with Renault engines as the LéO 213. One aircraft was produced as the LéO 21S fitted as a 10-stretcher ambulance. The first production LéO 213 was built in 1928 and a total of eleven were built and operated on routes from Paris to London, Lyons, Marseilles and Geneva. The LéO 213 had an increased wingspan, improved sound proofing and three baggage holds. When modified for night services they were re-designated as LéO 213N. In 1934 all the surviving LéO 213s were bought by the Armée de l'Air (French Air Force) and were converted to transports for 14-troops on bench seats and re-designated LéO 214.