Judge became the third Yankees player ever to homer on his birthday at Fenway, socking a two-run blast in the second inning en route to New York's 3-1 win over the rival Boston Red Sox.
The young right fielder is the first Yankee to homer in Boston since Roger Maris did so on his 32nd birthday on Sept. 10, 1966. Yogi Berra also went deep on his 22nd birthday at Fenway on May 12, 1947.
Judge has a team-leading seven homers and 15 RBIs for New York (12-7), which had lost three of its last five games.
The fun continued for Judge in the bottom of the third when he went barreling into the right field stands in foul territory chasing a fly ball.
"I honestly really didn't think about it. I just saw a ball I could get to and trying (to do) everything I can to catch it," Judge said of his highlight-reel catch.
The call on the field was no catch, but replays showed that he caught the ball, and the ruling was overturned after a challenge by Yankees manager Joe Girardi.
"It's his birthday, so it didn't seem (right) to ruin the day," Girardi said.
Judge's heroics were supplemented by a strong start from Yankees right-hander Luis Severino (2-1), who limited the Red Sox to three hits in seven scoreless innings while striking out six.
It was Severino's first career win at Fenway in three appearances (two starts). His ERA at Fenway before Wednesday's game was 9.53.
"My confidence right now is very good," Severino said. "I was making good pitches. I wasn't thinking about left field, the Green Monster, whatever. I was trying to throw everything, throw my secondary pitches for a strike."
Greg Bird also drove in a run for the Yankees.
Porcello (1-3), the Reigning American League Cy Young Award winner, struggled with his command, walking four while allowing all three runs (two earned) on five hits while striking out nine in 6 2/3 innings.
It was Porcello's first start with at least four walks in a span of 88 regular-season outings dating back to May 29, 2014, when he walked six against the Oakland Athletics as a member of the Detroit Tigers.
"I think the sinker and the four-seamer and the combination of both was pretty solid today," said Porcello, who lost only four games last season. "... The walks come back to hurt you so got to limit that."
Chris Young drove in a run for the Red Sox (11-9), who have dropped four of their last six.
Judge launched a first-pitch fastball from Porcello into the bullpens in right field for an opposite-field homer with a runner on first and nobody out in the second.
"Doesn't matter where he hits it," Girardi said of Judge. "If he puts the barrel to it and gets it in the air, it's got a good chance to go out."
Bird gave the Yankees a three-run lead on his line drive off the Green Monster in left with two out in the sixth, allowing Judge to score from second.
Dellin Betances relieved Severino in the eighth and pitched a scoreless frame with two strikeouts before Aroldis Chapman came on for the ninth.
Chris Young's groundout plated Benintendi from third to put the Red Sox on the board. Betts took third on a Chapman wild pitch with Hanley Ramirez at the plate.
Ramirez walked but Jackie Bradley Jr. struck out swinging and Josh Rutledge also fanned swinging as Chapman notched his fifth save.
Rutledge teased a walk-off, three-run homer on the second-to-last pitch of the game, but the ball sailed well left of the foul pole on the Monster.
"Everything (Chapman) throws is hard, so really I wasn't trying to do too much," Rutledge said. "I was just trying to play pepper with him, you know?"
NOTES: New York and Boston entered Wednesday's game having split their last 166 meetings over the past nine seasons (83-83), with the Yankees going 42-42 at Yankee Stadium and the Red Sox going 41-41 at Fenway Park. ... Red Sox 2B Dustin Pedroia (left knee sprain) did not play despite manager John Farrell saying he would have been available had Tuesday's series opener not been rained out. "I did some activities yesterday, kind of tested it out a little bit. Just a little sore," Pedroia told WEEI.com. Pedroia was injured on a controversial slide by Baltimore 3B Manny Machado on Friday. ... Boston RHP Matt Barnes dropped the appeal of his four-game suspension for throwing at Machado on Sunday in retaliation to his slide. ... Yankees RHP Masahiro Tanaka (2-1, 6.00 ERA) counters Red Sox LHP Chris Sale (1-1, 0.91 ERA) in Thursday's series finale.