Benji Michel also scored his third goal of the year before half-time for Orlando (7-3-4, 25 points), which snapped a three-match winless run. The victory that vaulted the hosts above Philadelphia (6-4-5, 23 points) into second place in the Eastern Conference standings.
Mauricio Pereyra picked up his team-leading fifth and sixth assists of the year and Nani added his fourth for the Lions, who improved to 4-1-2 at home. Nani had a minor limp as he left the game in the 83rd minute.
Kacper Przybylko scored his team-leading fifth goal to pull the Union within 2-1 in the 68th minute. Philadelphia outshot Orlando 18-5 but only threatened an equalizer deep in second-half stoppage time.
Now in third place, the Union have only one win in their last five games, and they have yet to win a match in which they conceded more than one goal.
Michel put Orlando in front in the 10th minute. With Pereyra on the ball, Michel snuck away from the watch of his defender, held his run to remain onside, ran onto Pereyra's well-weighted through ball and then drove a low finish past goalkeeper Matthew Freese.
It was 2-0 in the 59th minute. After Orlando took a free kick short on the left side, the ball eventually came to Nani on the right. Nani looped in a cross toward the penalty spot, where Perea met it with a flick-on header that nestled inside the left post.
Philadelphia cut it to 2-1 nine minutes later when Przybylko reached Olivier Mbaizo's cross from the right and hammered a first-touch finish between Gallese and the right post.