Vale made a fast start and took a third-minute lead through Tom Pope's 15th goal of the season.
Adam Yates' right-wing cross was headed on by Ben Williamson and Pope had the freedom of the six-yard box to fire a right-foot shot past Owain Fon Williams.
Tranmere were all over the place in the opening stages, but they gradually improved and Ryan Lowe should have equalised before the break.
The contest then burst into life with four goals in the opening 15 minutes of the second half.
Vale looked home and dry after Billy Knott arrowed a low left-foot shot inside Fon Williams' left-hand post in the 47th minute and Williamson slipped a low right-foot effort past the visiting keeper from eight yards in the 56th minute.
But Tranmere reduced the arrears in the 58th minute when big defender Ash Taylor buried a towering header inside Chris Neal's left-hand post from Jason Koumas' right-wing corner.
And it was game on two minutes later when Koumas curled a 35-yard free-kick which sailed over everyone and drifted inside Neal's left-hand post.
But Vale held on and could have extended their lead as Doug Loft struck and crossbar before Pope squandered two gilt-edged chances.