He sat as a Liberal Member of Parliament for Montgomeryshire between 1880 and 1894, and was recognised as the leader of the Welsh MPs.

A close friend and associate of William Ewart Gladstone, he was recognised as the leader of the Welsh members of parliament.

On his retirement from the House of Commons in 1894 he was raised to the peerage as Baron Rendel, of Hatchlands in the County of Surrey.

[5] Apart from his political career, Rendel was a benefactor to the University College of Wales at Aberystwyth and served as its president from 1895 to 1913.

[2] Rendel's eldest daughter, Rose Ellen, married Harry Goodhart, a former international footballer who became Professor of Latin at the University of Edinburgh.