Jacobus Mattheüs de Kempenaer (6 July 1793 – 12 February 1870) was a Dutch politician and lawyer who served as Chairman of the Council of Ministers from November 1848 to November 1849.

Initially in the House of Representatives, de Kempenaer was considered a liberal.

De Kempenaer was appointed to the Constitution Commission headed by Johan Rudolph Thorbecke in 1848, and as Minister of the Interior.

He soon became de facto Prime Minister, playing an important role in the revision of the national Constitution.

De Kempenaer was married in Haarlem on 19 August 1818 to Arnoldina Jacoba Gerlings (1796–1871).