It was discovered on 17 March 1939, by Finnish astronomer Yrjö Väisälä at Turku Observatory on the coast of southwestern Finland.
[2] Porvoo orbits the Sun in the inner main-belt at a distance of 2.1–2.6 AU once every 3 years and 7 months (1,317 days).
[8] In the early 1980s, a rotational lightcurve of Porvoo was obtained from photometric observations taken by American astronomer Richard P. Binzel using the 0.91- and 2.1-m telescopes at the University of Texas McDonald Observatory.
[3] This minor planet was named for Porvoo, Finnish city and municipality located on the southern coast of Finland, and east of the capital Helsinki.
[2] Porvoo is one of the six medieval towns in Finland, and is its second oldest city after Turku, location of the discovering observatory.