Édouard Joseph Mercier (1 April 1799 - 18 January 1870) was a Belgian politician of liberal tendencies.

In 1837, he was a liberal (and from 1843 Catholic) member of parliament for the district of Nivelles and held this office until 1857.

He participated in the Unionist ministry of Peter Decker as Minister of Finance (1855-1857).

At the time of the unrest that followed the vote of the "convents of law" (May–June 1857), he argued with Alphonse Nothomb the thesis that we should not give in to pressure from the street.

After the local elections of October 1857, which was a defeat for the Catholics, he opposed Nothomb with the resignation of De Decker, but could not prevent it.