Kogarah MP Chris Minns said the Labor Party needed to "turn to a new generation of leadership" when he launched his bid to become state leader at Carss Bush Park.
Mr Minns, 39, who was elected Kogarah MP in 2015 and is the party's spokesman on water, was accompanied to a media conference by his wife Anna and children, Joseph, 11, Nick, eight and George, two.
Transport spokeswoman Jodi McKay is also expected to stand for the job. Ms McKay was a journalist before entering parliament in 2007 at the age of 37.
Mr Minns promised a "fresh and new approach", with the priority issues being changes to the planning system "to make Sydney a more liveable city", and climate change.
Unless the party changed it would not survive as a political movement, he said.
"I believe we should turn to a new generation of leadership. We should have new ideas and a fresh approach.
"We have to provide answers to the pressing problems facing NSW and, if we don't do that, we are going to continue to fail at the ballot box."
The son of a school principal, Mr Minns has been a member of the NSW ALP since 1998 and also served as NSW ALP assistant general secretary and chief of staff to the Minister for Energy.
He holds an undergraduate degree from the University of New England in Armidale and won a full scholarship to Princeton University in the United States where he was awarded a Masters in Public Policy (2012-13).
Mr Minns was a retained firefighter from 2006 to 2007 while studying at university. He was also government relations manager at Inspire Foundation, a youth mental health charity from 2008 to 2009.
Mr Minns was also deputy mayor of Hurstville for a brief period.
Mr Minns said he would detail his "positive plans" for change to rank and file Labor members in forums across the state and talk directly with parliamentary caucus colleagues.
He also said he would be putting forward policies on the economy, health, education, rural and regional areas.
