Mr Mulherin was Primary Industries and Fisheries minister under former premier Peter Beattie before going on to hold the portfolio for Rural and Regional Economies in the Bligh government.

Following Labor's crushing 2012 election defeat he hung on, becoming deputy opposition leader to now-Premier Annastacia Palaszczuk.

The premier said Mr Mulherin had a heart "as big as Queensland".

"I've lost a friend but Queensland has lost a champion," she said in a statement on Monday.

Born and raised in Mackay, Mr Mulherin served as its state representative from 1995 until 2015, when he retired for family and health reasons.

Mr Mulherin had made an enormous contribution to the Labor Party, Treasurer Cameron Dick said.

"The current face of Mackay was chiselled by the hands of Tim Mulherin."

A family man, the loss was a double blow to Mr Mulherin's family, coming as it did on Father's Day, Mr Dick told reporters.

His love for Mackay was second only to his love for his family, Ms Palaszczuk added.

"His pride and love for them was boundless and on constant display," she said.

Mr Mulherin is survived by his wife, Erin, and three sons.

Australian Associated Press