Dean Glover made one change to his starting 11, with Robert Taylor making a rare start on the left of midfield to replace Scott Brown.
And the former Nuneaton Borough man justified his inclusive with his side's second and winning goal early in the second half.
The visitors had started brightly and almost went in front when Ian Miller met David Poole's corner only for Paul Edwards to hack the header off the line.
And Darlington took the lead after 26 minutes when Danny Carlton escaped his marker from Steve Foster's quickly taken free-kick and fired a low shot past Joe Anyon.
Liam Hatch was giving the Vale defence a torrid time and the forward teased Anthony Griffith once more, but sent his 37th minute shot just wide of the right-hand post.
However in time added on, Kevin Gall's cross found Louis Dodds in the area and his shot took a deflection on its way into the net to give Vale an equaliser they barely deserved.
The visitors, who have now gone six games without a win and remain in administration, were stung once more just five minutes into the second period as Taylor fired across Andy Oakes from Paul Marshall's pass.
The goal unearthed a completely different Vale team who then produced some attractive attacking football as their confidence flowed.
And it was little surprise when Marc Richards converted Dodds' 77th minute cross from the right for his 11th of the season to seal only Vale's sixth home win of the campaign.