Mr Helper will not contest the state election in 2014. He said he had considered the decision for a long time.
"It's the halfway mark of the term and it's on the eve of redrawing of the electoral boundaries," he said.
"It's the right time. It's giving my party time to select a good candidate."
Mr Helper became Member for Ripon in 1999.
He said he had enjoyed many personal and party achievements in the years since.
"In a general sense there's the transformation of the degree of competence and resilience of the people represented in Ripon," he said.
"It's a result of both the Bracks and Brumby governments. Being part of that was an achievement for me."
Mr Helper said other achievements included being Minister for Agriculture and Minister for Small Business for four years.
He said he was proud of his role in developments as minister.
"They include the development of the Future Farming Strategy because it set in place a direction of working with farmers that will stand the test of time," he said.
"Governments of the day may call it different things and they may fund it more or less, but into the future, it will change for the better the way we work with agriculture.
"While it was a tough political ask, the decision to end the moratorium on growing GM canola was also the right call."
Mr Helper said he also took pride in helping to return passenger rail to Ararat and Maryborough.
He said he had enjoyed his time as the Member for Ripon.
"It has been an honour and privilege to work with and for the people, families and communities that make up Ripon," he said.
He said he looked forward to retirement.
"Everyone who has a busy life builds up a whole lot of things they want to do when they get time," he said.
"For me, it's travelling and fishing albeit I'm not very good at it.
"I do look forward to pottering around in the garden. That will interest me very much beyond 2014.
"There may well be one or two causes I'm interested in and will want to continue but we will look at that as it gets closer."