Durant, who hadn't played since December 16 as the Nets grappled with a Covid spike that eventually saw three of their games postponed, picked up where he left off with 33 points.
James Harden added a triple-double of 33 points, 14 rebounds and 10 assists. But it wasn't enough for the Eastern Conference-leading Nets against a Sixers team that played without coach Doc Rivers on the sideline because of coronavirus concerns.
Teams across the league were coping with Covid as the Omicron variant fueled a surge around the United States.
The NBA cancelled Thursday's clash between the Western Conference-leading Golden State Warriors and Denver because the Nuggets, hit by Covid and injuries, couldn't field the requisite eight players.
That decision sparked a sharp response from Warriors star Draymond Green, who would have been absent himself because of Covid.
Green took issue with the 11th postponement of the season, saying cancelling games piecemeal as the league presses ahead with its season was unfair.
"How do you continue to cancel games when you've implemented rules to prevent this from happening?" Green said on Twitter. "Is that not a competitive advantage for other teams?
"The guys we didn't have due to the protocol list played no role in Tuesdays loss? Pick a side but don't straddle the fence."
Green was among the Warriors absentees when Golden State came up short in an 89-86 loss to the Nuggets in San Francisco on Tuesday.
Now, he said, a rescheduled game will likely add a back-to-back to the Warriors schedule and let the Nuggets play the Western Conference co-leaders "at full strength ... But they got to sneak a win when we weren't at full strength, only two days ago???
"Let's make it make some sense here."
NBA commissioner Adam Silver has insisted he sees no reason to pause the season. And in a bid to keep teams on track the league has made it easier for teams to call up players on short-term contracts from the developmental league and reduced the number of days that vaccinated, asymptomatic players must isolate after a positive test.
But the sheer number of cases means some teams have still been caught out as Covid combines with mid-season injuries to sideline players.
That's why the Nets were thrilled to welcome back Durant, who missed three games.
Even with Durant and Harden, however, the Nets couldn't hold off the Sixers.
In a game that featured four lead changes in the fourth quarter, Embiid converted a three-point play with 3:14 remaining to put the 76ers up 100-97.
Philadelphia wouldn't relinquish the lead, Tyrese Maxey and Seth Curry draining late three-pointers to push the 76ers over the line.
With 15 seconds left Durant and Embiid exchanged words and were separated by teammates, each receiving a technical foul.
"We just respect each other so much, that natural competitive fire comes out," said Durant, who exchanged a thumbs-up sign with Embiid as players departed the court after the game. "It's the name of the game... We love competition, and this is only going to make it better."
Maxey said the victory, after two defeats this season to the Nets, was a "big win."
"Coach Doc went down and we had a couple of players in the protocols, we wanted to come here and make a statement," he said. "They already beat us twice so to come here and get a win on their court is big."
In Orlando, two-time NBA Most Valuable Player Giannis Antetokounmpo scored 33 points to lead the reigning champion Milwaukee Bucks to a 136-118 victory over the Magic.
Jrue Holiday added 25 points and Khris Middleton scored 22 for Milwaukee, who won their fifth straight.
The Washington Wizards, buoyed by the return of Bradley Beal from Covid protocols, beat the Cleveland Cavaliers 110-93.
Beal scored 19 points and handed out 10 assists in his first game in almost two weeks.