It was a real smash and grab raid by Millwall who had been under the cosh for much of the game.
But their battling qualities pulled them through as they bounced back from falling behind to a strike from Carl Cort - his sixth of the season and fifth in three games.
Former Wolves' midfielder Jermaine Wright, on his debut after his arrival on a three-month loan from Leeds United, fired Millwall back on level terms with a stunning 27th minute volley.
Millwall were then indebted to goalkeeper Andy Marshall for keeping them on level terms before Hayles latched on to David Livermore's through ball to grab his late, late strike.
It marked a triumphant return to Molineux for Millwall boss Colin Lee, who had been in charge at Wolves for two years between 1999 and 2001.
Millwall, who had collected just one point from their previous seven games, were also the last team to win at Molineux as they ended Wolves' unbeaten 17-game home run.
Wolves had been chasing an eighth successive home win but they failed to build on Cort's opener. They peppered the Millwall goal but could not find a way past Marshall.
Before Cort struck Jody Morris cleared off the line from Ki-Hyeon Seol and Mark Kennedy wasted two clear chances.
But their pressure eventually told after 19 minutes when Kennedy fed Jackie McNamara on the right wing.
Scottish international McNamara lifted in a cross that Cort headed past Marshall.
That looked set to signal the start of a goal avalanche for Wolves only for Millwall to leave the Molineux faithful reeling through Wright's strike.
There appeared to be no danger when Kennedy headed away a corner from Morris but his clearance fell straight on to the left foot of Wright whose first-time volley whistled past shocked goalkeeper Michael Oakes from 25 yards.
That was the only time that Millwall threatened in the first period and Wolves should really have been back in front by half time only for Marshall to deny Leon Clarke and Cort with smart saves.
Marshall continued his heroics in the second half when he again saved from Cort and Rohan Ricketts, while Clarke missed an open goal after failing to convert a Cort knockdown.
They proved to be costly misses as Hayles made them pay the ultimate price to send Millwall's small army of travelling fans into ecstasy.