Port Vale were rarely seen as an attacking force in a disappointing display and remain far from safe.
It took Tranmere until the 28th minute to break through. Calvin Zola netted his first goal since December after an interchange of passes with Chris Greenacre.
Mark Goodlad in the Vale goal produced good saves from Delroy Facey and Jason McAteer before Zola headed just over from a Gareth Roberts cross in the 41st minute.
Tranmere continued to dictate in the second half after Ian Goodison replaced Ian Sharps.
Steve Jennings was just wide with a free-kick but Rovers doubled their lead in the 58th minute. Stephen O'Leary fired home from close range from a headed pass by Zola.
Goodison produced a headed clearance off the line from a Craig James header following a rare Vale attack.
Facey fired against a post for Tranmere in the 74th minute but they made the game safe five minutes later.
Goodlad could not hold a well struck shot by substitute Steve Davies after a good run by David Raven.
Raven almost made it four in the 86th minute but his shot found the side netting.
O'Leary was excellent in the Rovers midfield. Skipper George Pilkington and Chris Birchall tried hard for the visitors but they were a clear second best on the night.