Strikes from Louis Dodds, Robert Taylor and Marc Richards gave the visitors the win despite the Hatters dominating for long periods.
But the hosts failed to make the most of their chances, finding the net only through Sam Parkin in the 35th minute.
After making 11 signings the day before the game, Luton handed full debuts to six players - Claude Gnakpa, George Pilkington, Ian Roper, Rossi Jarvis, Asa Hall and Chris Martin - while Kevin Nicholls made his second debut after returning to the club from Preston.
Roared on by a vociferous home crowd, the Hatters began brightly with Martin's diving header from Lewis Emanuel's fifth minute free-kick flying over, before Martin fired wide left-footed from the edge of the area three minutes later.
Luton kept up the momentum with Hall firing a left-footed shot just wide from 18-yards in the 16th minute and, three minutes later, Joe Anyon appeared to punch a Nicholls corner against his own post before Taylor cleared.
Incredibly it was the Valiants who opened the scoring completely against the run of play in the 25th minute.
Martin was caught in possession in his own half and Richards found Dodds who expertly fired an instant drive into the bottom corner with the outside of his right foot from 20 yards.
The home side eventually found the net in the 35th minute when, from their 11th corner of the half, Nicholls' kick allowed Parkin to glance home from 10 yards.
But in first-half stoppage time the visitors went back in front when Sol Davis badly misjudged Anyon's long kick allowing Richards to run into the area past Roper and cross for Taylor to tap in from a yard out.
Luton again forced the pace in the second half with Parkin heading Gnakpa's cross wide in the 54th minute, but more comical defending let the Valiants extend their lead four minutes later.
Home goalkeeper Dean Brill was left red faced when he mis-hit a clearance to Kyle Perry who crossed from the left for Richards to fire home left-footed from 15 yards in off the crossbar.
Martin saw a scuffed effort saved by Anyon in the 73rd minute, but Vale should have stretched their lead 60 seconds later when substitute Luke Rodgers sprinted clean through only to shoot past the post.
Luton's day was summed up when Martin crossed to find Parkin in acres of space seven minutes from time, but the former Swindon man could only shoot wastefully wide from 15 yards.