Brynjólfur Pétursson (15 April 1810 – 18 October 1851) was an Icelandic lawyer and government official.
Brynjólfur was born in Víðivellir in Skagafjörður and was one of the "Víðvellir brothers", the sons of profast Pétur Pétursson and his second wife, Þóra Brynjólfsdóttir.
Brynjólfur died an unmarried man in Copenhagen in 1851, leaving no children.
Brynjólfur graduated from Bessastaðir in 1828 and attained a degree in jurisprudence from the University of Copenhagen in 1837.
In his student years, Brynjólfur was one of the Fjölnismenn along with Jónas Hallgrímsson, Konráð Gíslason and Tómas Sæmundsson.