He was a Liberal member of the Legislative Assembly of Ontario who represented the riding of Thunder Bay—Superior North from 1995 to 2022 (known as Port Arthur from 1995 to 1999).

He also worked as a publicist for the Canadian Broadcasting Corporation, and was a founder of the North of Superior Film Association.

[2] The election was won by the Progressive Conservative Party of Ontario, and Gravelle joined 29 other Liberals in the opposition benches.

[3] In the provincial election of 2003, Gravelle was re-elected with 72.5 per cent of the popular vote, the highest percentage total in the province.

In February 2013, Kathleen Wynne moved him back to the position of Minister of Northern Development and Mines.