Doncaster Rovers are still seeking their first League One win and manager Paul Dickov could hardly hide his frustration.
Thorsten Stuckmann saved Sam Foley’s 11th-minute penalty before Vale took charge through Foley’s 35th-minute header, Uche Ikpeazu’s 46th-minute strike and Byron Moore’s backheel a minute from time.
Ikpeazu was on loan at Doncaster from Watford last season but cut short his stay because he was not playing enough.
Dickov said: “We were poor and sluggish from start to finish. We have to give Vale a lot of credit because they caused us problems all afternoon, but our performance was just not good enough.
“We defended and played as individuals. If you don’t do the basics right you give yourself no chance and that is what happened today.
“When you lose the ball, you have to go and win it back. We just didn’t do that and Vale kept coming at us.
“Our second-half performance was an improvement, but to concede a second goal so soon after half-time was criminal. It gave us no chance really.
“Uche caused trouble all afternoon. We couldn’t handle him at all.
“It’s a bad day and we have to recover from this and prepare for the next game. There are lessons to learn and there is some hard work to do on the training ground.”
The scoreline would have been much worse had it not been for Stuckmann, who made a string of saves in the first half.
Port Vale: Alnwick, Purkiss, Inniss, Duffy, Dickinson, Moore, Grant, Andoh (Daniel 70), Foley, Dodds, Ikpeazu (Leitch Smith 76). Unused substitutes: Johnson, Birchall, Streete, Brown, Kelly.
Doncaster Rovers: Stuckmann, McCullough, MacKenzie, Butler, Taylor-Sinclair, Coppinger, Wellens, Middleton (Main 46), Chaplow, Evina (Whitehouse 58), Williams. Unused substitutes: Marosi, Lund, Jones, Mandeville, P McKay.
Referee: R Lewis (Shropshire).
Man of the match: Thorsten Stuckmann.