The Katajanokka Airport (Finnish: Katajanokan lentosatama) was the first airport in Finland, located in the Katajanokka neighbourhood in Helsinki. It functioned as a seaplane base in the south-eastern shore of Katajanokka during the years 1924–1936. Its history ended when the Helsinki-Malmi Airport was inaugurated on 16 December 1936.

Aero Oy began its flights from Katajanokka on 20 March 1924 at 15:40 with a Junkers F 13 D-335 aircraft. The crew consisted of a German pilot and a mechanic. The first Finnish pilot, Gunnar Lihr, began his flights during the summer of the same year. The routes of Aero went to Stockholm, Tallinn and Riga. From the very start, the company had two flights to Tallinn on every day of the week. Stockholm was not as popular as Tallinn, with six flights a week. The flight to Stockholm took three hours, but in the event of contrary winds, the flight time could be up to half an hour longer.