Martin Wegelius (10 November 1846 – 22 March 1906) was a Finnish composer and musicologist, primarily remembered as the founder, in 1882, of the Helsinki Music Institute, now known as the Sibelius Academy.

Wegelius studied in Leipzig, Vienna and Munich. He had intended to pursue a career as a composer, and wrote a handful of orchestral works and a significant number of chamber and vocal works. He was a particular admirer of Wagner but wrote predominantly in the Romantic style. After founding the Institute he had little time for composing, and appears to have concentrated exclusively on teaching. The most famous graduate of Wegelius' Institute was Jean Sibelius.

He is often compared with his contemporary and rival Robert Kajanus, founder of the Helsinki Symphony Orchestra, the first professional symphony orchestra in the Nordic countries.