Though the visitors hit the lead twice in the first half at Exploria Stadium, the Lions equalised as many times, including a finely taken goal from Alexandre Pato in the 36th minute.
Sensing where the ball would drop following Mauricio Peyeyra's ball over and into the penalty area, Pato set himself and calmly volleyed past Maxime Crepeau.
Ilie Sanchez rifled home a mere six minutes into the second half and from there, LAFC were able to sit and absorb Orlando pressure.
After some important saves from Crepeau to deny a third equaliser, substitute Kwadwo Opoku was able to score an injury-time sealer in transition, moving Steve Cherundolo's side to four wins and a draw from five games.
Meanwhile, Philadelphia Union were able to keep their place atop the Eastern Conference, with a 2-0 win at home to Charlotte FC.
The Union took the lead after only four minutes and in uncomplicated fashion, with Sergio Santos running on to a ball over the top and assisting for Julian Carranza from the byline.
Daniel Gazdag doubled the margin a minute within the restart, and similarly to LAFC, absorbed pressure in their defensive half to see out the win to move to 13 points from five games.
NY Red Bulls and Atlanta stayed within three points of Philadelphia in the Eastern Conference with respective 1-0 victories over New England Revolution and DC United. Columbus Crew dropped points at home to Nashville, with Alex Muyl's lone goal the difference.
A Gonzalo Higuain penalty would not suffice for Inter Miami, who remain rooted to the bottom of the ladder in the East, after Phil Neville's side losing 3-1 to Houston Dynamo. Chicago Fire and FC Dallas played out a goalless draw, while Toronto FC beat reigning MLS Cup champions New York City 2-1.
In the Western Conference, Real Salt Lake fell two points behind with a 1-1 draw away to Colorado, Austin FC conceded two goals in as many minutes to eventually play out a 2-2 draw against San Jose Earthquakes.
Ryan Raposo's 73rd-minute winner was enough for Vancouver Whitecaps at home to Sporting KC, while Brent Kallman's own goal eventually condemned Minnesota to their first defeat of the season, losing 2-1 to the Seattle Sounders.
LAFC led twice in the first half at Exploria Stadium but were pegged back on both occasions, first by a finely taken goal from Alexandre Pato in the 36th minute.
Sensing where the ball would drop following Mauricio Peyeyra's delivery into the penalty area, Pato set himself and calmly volleyed past Maxime Crepeau.
But Ilie Sanchez rifled in a third LAFC goal six minutes into the second half and the visitors were able to absorb Orlando pressure thereafter.
After some important saves from Crepeau, substitute Kwadwo Opoku sealed victory in stoppage time, moving Steve Cherundolo's side to 13 points from five games after four wins and a draw.
Meanwhile, Philadelphia Union were also able to keep their place atop the Eastern Conference with a 2-0 win at home to Charlotte FC.
The Union took the lead in uncomplicated fashion after only four minutes, with Sergio Santos running onto a ball over the top and crossing for Julian Carranza from the byline.
Daniel Gazdag doubled the lead a minute into the second half, with that two-goal margin enough for the Union to see out the win and themselves move to 13 points.
New York Red Bulls and Atlanta United stayed within three points of Philadelphia in the East with respective 1-0 victories over New England Revolution and DC United. Columbus Crew lost at home to Nashville, with Alex Muyl's lone goal the difference.
A Gonzalo Higuain penalty counted for little for Inter Miami, who remain rooted to the bottom of the ladder in the East after Phil Neville's side lost 3-1 to Houston Dynamo. Chicago Fire and FC Dallas played out a goalless draw, while Toronto FC beat reigning MLS Cup champions New York City 2-1.
CF Montreal edged FC Cincinnati in a seven-goal thriller, trailing twice in the first half before recovering to win 4-3.
In the Western Conference, Real Salt Lake fell two points behind with a 1-1 draw away to Colorado Rapids, while Austin FC conceded two goals in as many minutes to draw 2-2 against San Jose Earthquakes.
Ryan Raposo's 73rd-minute winner was enough for Vancouver Whitecaps at home to Sporting Kansas City, while Brent Kallman's own goal ultimately condemned Minnesota United to their first defeat of the season, losing 2-1 to Seattle Sounders.
Alexandre Pato's 94th-minute free-kick cannoned into the crossbar, with Andres Perea forcing home the rebound, ushering in scenes of celebrations as it would have sealed a post-season berth for Orlando.
That jubilation turned into frustration when the goal was later disallowed after referee Allen Chapman consulted the video, deeming Daryl Dike committed a foul on Alistair Johnston amid the goal-line scramble.
"It's a very sad day for the league," Orlando head coach Oscar Pareja said. "There is no explanation on a play that we saw evident. And it destroyed the joy of our people."
United States international Dike had earlier opened the scoring in the 18th minute, before Hany Mukhtar levelled it up for Nashville eight minutes into the second half.
Orlando – fifth in the Eastern Conference – can still reach the play-offs if they beat Montreal on the final day of the season on Sunday, while Nashville are third.
Philadelphia Union moved above Nashville into second in the east with their routine 2-0 home victory over struggling FC Cincinnati.
The Union are ahead of Nashville on goal difference only, with strikes from Daniel Gazdag and Paxten Aaronson securing the win.
Cincinnati are eight points adrift at the foot of the table and have lost 11 games in a row and 14 of their past 15, while they have only one win in their past 24 games.
Elsewhere, Minnesota United stayed firmly in the play-off hunt thanks to a 2-1 home win over Western Conference leaders Sporting Kansas City.
Dominique Badji's 58th-minute goal was enough for Colorado Rapids to edge Houston Dynamo 1-0, meaning they tied their club record for points in a season with 58.
Former Milan, Chelsea and Brazil attacker Pato had his contract with Sao Paulo mutually terminated last August and had been hoping for a return to Europe.
However, the 31-year-old will continue his career in MLS with Orlando, who fell to New England Revolution in the Eastern Conference semifinals last season.
"We are very excited to welcome Pato to Orlando. He's a veteran player who has featured at some of the top clubs around the world and has a proven track record at the international level," said Orlando executive vice-president of soccer operations Luiz Muzzi.
"The experience that Pato brings with him will be invaluable to the club. Pato is a high-calibre player and we're excited to add another great target up top."
Pato was one of the most highly rated young players in world football when he left Internacional for Milan in 2007, but his career stagnated due to injuries.
After largely unsuccessful stints at Corinthians, Sao Paulo, Chelsea and Villarreal he joined Tianjin Tianhai in the Chinese Super League and rediscovered his scoring touch with 30 goals in 47 Chinese Super League games.
He failed to maintain that form after returning to Sao Paulo in 2019 on a three-year contract and departed after dropping down the pecking order.
Caden Clark had put the Red Bulls up with a spectacular goal early in the second half but last season's Western Conference top spot finishers hit back.
Gadi Kinda netted a 59th minute penalty with Hungarian forward Daniel Salloi putting KC ahead barely 60 seconds later with a simple close-range finish.
New York City were also opening day losers, blowing a 1-0 lead to go down 2-1 at D.C. United.
City, who reached last season's play-offs, went ahead on the quarter hour from Valentin Castellanos.
But United responded by taking the lead before the interval with a sensational long-range drive from Brendan Hines-Ike and another from Russell Canouse, coming from a perfectly executed corner routine.
10-man Revolution hit back, Pato debut
Last season's semi-finalists New England Revolution fought back from two goals down to claim a thrilling 2-2 draw away to Chicago Fire.
Revolution, who were reduced to 10 men in second-half stoppage time after a DeJuan Jones red card, trailed 2-0 after 11 minutes following goals from Robert Beric and Luka Stojanovic.
Polish attacker Adam Buksa and Gustavo Gou netted in the following 15 minutes to level the match.
New England debutant Edward Kizza should have scored the winner when he struck the crossbar with an 87th minute header.
Victor Wanyama was among the goals as Montreal eased past Toronto 4-2 in their Canadian clash, while former Brazil international Alexandre Pato debuted for 2020 quarter-finalists Orlando City who had a scoreless draw with Atlanta United.
However, Pato limped off in the 80th minute with an apparent knee issue which will have Orlando sweating on scans.
Los Angeles FC started the new season with a solid 2-0 victory at home over newcomers Austin with goals from Corey Baird and Jose Cifuentes.
Nashville fought back from a two-goal deficit to draw 2-2 with Cincinnati thanks to Randall Leal's 64th minute long-range curler, while Dallas and Colorado also played out a 0-0 draw.
Premature substitution
LAFC coach Michael Bradley admitted he "might have jumped the gun" when he accidentally subbed off star Mexican attacker Carlos Vela in the 22nd minute after he waved in his direction. In hindsight, Vela was calling for treatment from a trainer after picking up a knock.
Teenager's special strike
The Red Bulls went ahead when 17-year-old midfielder Clark fired in a superb volley out of mid-air. The teenager appears a star in the making.
Saturday's results
Montreal 4-2 Toronto FC
Orlando City 0-0 Atlanta United
Los Angeles FC 2-0 Austin
Sporting KC 2-1 New York Red Bulls
FC Dallas 0-0 Colorado Rapids
DC United 2-1 New York City FC
Chicago Fire 2-2 New England Revolution
Nashville 2-2 Cincinnati
Galaxy in Florida
There's three games on Sunday including a glamour fixture between David Beckham's Inter Miami against his former club Los Angeles Galaxy.
