Senior NSW Liberal MP Don Harwin has revealed he is gay in a speech to the NSW Legislative Council, crediting his private struggles with giving him the determination needed to succeed in Parliament.

The president of the upper house made the revelation in a Christmas message on the last sitting day of Parliament for the year on Thursday. He joins just a handful of openly gay NSW MPs, including Labor's Penny Sharpe and Helen Westwood, Liberal Bruce Notley-Smith and independent Alex Greenwich.

Coming out: Upper house president Don Harwin. Credit:Dallas Kilponen

An emotional Mr Harwin told the chamber he rejoiced in the opportunities available to young gay and lesbian people nowadays.

"Life is so different for them than it was for me," he said.