After 15 rounds, Brondby were right at the top of the table, but after three successive defeats to end the fall season, Brondby head into the winter break in third place, nine points adrift of AGF who top the table.
Despite the win Vejle remain bottom of the league, but are now only six points behind Silkeborg in the 10th spot which will avoid relegation.
In a dramatic second half Brondby goalkeeper Patrick Pentz was red carded, and Jelle Duin took advantage of it to score the winning goal with ten minutes remaining.
Brondby were otherwise all-dominant in the first half despite missing Noah Nartey and Marko Divkovic, who were suspended for red cards most recently against Fredericia.
Vejle struggled epecially to contain the threat of Brondby's Oliver Villadsen and, in particular, Sho Fukuda who created great chances in the first half for Nicolai Vallys and Stijn Spierings without Brondby being able to take advantage.
Vejle took the initiative straight from the start of the second half and were rewarded four minutes after the interval, when Mike Vestergaard drove the ball far into the Brondby half and following a deflection the ball landed at the feet of Christian Gammelgaard who finished clinically past Pentz.
Brondby dug themselves back into the game and restored parity after 72 minutes when Michael Gregoritsch produced a flat delivery for Fukuda who was left with an easy finish.
The visitors' celebrations on the pitch was, however, cut short as Vejle won a penalty three minutes later when Pentz mistimed a clearance and ended up kicking Bismark Edjeodji in the process. And Jelle Duin converted the chance in Vejle's second attempt after Thomas Mikkelsen saved the first attempt from Mads Enggaard but Mikkelsen was adjudged to have moved too soon.
Brondby attempted to get back into the match, but Vejle held on for a sensational win.