Leeds trailed to Danny Welbeck's 21st-minute Seagulls strike in Sunday's contest at Elland Road and looked to be heading for a fourth consecutive defeat that would have left Jesse March's side in the Premier League's bottom three.
Struijk, though, came off the bench to head home a dramatic 92nd-minute equaliser that pulled Leeds above the dreaded dotted line at Burnley's expense.
The Clarets have an additional fixture remaining and a far better goal difference but United's plight is at least looking healthier than it would have done without Struijk's late leveller.
The defender's only other goal came in last season's 4-2 defeat at Arsenal and Struijk was left delighted by fulfilling a rather different brief and hailing the team mate who set his goal up.
Twenty-year-old striker Joe Gelhardt produced some brilliant skill to work space on the byline in a crowded area before delivering a perfect cross that Struijk headed home at the far post to send Elland Road wild.
"To be fair I haven't really seen it but I know he chipped it over the defender," said Struijk of Gelhardt to LUTV.
"He's really good, really talented on the ball and to find me at the back stick was really good.
"This is the most important goal I have scored and I'm really happy to get the point at the end because it's really important for us to take all the points we need and that we can."
Asked what instructions were given to him before coming on - and pressed if he was asked to go and score the equaliser, Struijk smiled: "I don't think this is really the instructions that you get - maybe as a striker.
"But as a defender and especially for us it is to keep them clear. To score the goal, that just comes with it sometimes."
"It was just a case of play your game, do what you have got to do.
"Of course in the back of your head this is one thing you always try."
Brighton served up five shots on target in the first half as part of ten attempts compared to United's eight, of which just two were on target.
Leeds, though, fired in 11 attempts during the second half, three of which needed saving by impressive Seagulls 'keeper Robert Sanchez.
"It was frustrating because I think in the second half as well we created a lot of chances," said Struijk.
"We were unlucky not to get a goal earlier and then we are in a race to get time to get one back and luckily we did."