The 47-year-old left-hander allowed nine runs on nine hits, including six doubles and Mike Lowell's two-run homer, and left after failing to retire any of the first four batters in the second inning. Boston added three runs in the third off David Herndon.
John Lackey (7-3) won his third straight decision, giving up two runs and six hits in seven innings.
All the runs against Moyer (6-6) were earned. He had given up between nine and 11 earned runs in five of his other 200 starts before Friday, but the shortest stint in those shaky outings was 3 2-3 innings. His career ERA at Fenway Park rose from 6.43 to 7.59.
Ortiz and Marco Scutaro each had three hits for Boston, which opened a nine-game interleague homestand against Philadelphia, Arizona and the Los Angeles Dodgers.
The Phillies lost for the 15th time in 22 games, a span in which they've managed just 53 runs.
Moyer walked the first batter he faced, Scutaro, who was forced out at second on Dustin Pedroia's grounder. Then the onslaught began with consecutive doubles by Victor Martinez, Ortiz and Adrian Beltre, and then Lowell's second homer of the year that made it 5-0.
Scutaro opened the second with a single before the next three batters, - Pedroia, Ortiz and Martinez - all doubled in runs.
Boston's ninth run scored when Lowell grounded into a double play. The Red Sox began the third with three straight hits off Herndon - singles by Mike Cameron and Darnell McDonald and an RBI single by Scutaro. Then Ortiz hit a two-run single with two outs.
Lackey allowed just a hit and a walk with two strikeouts in the first three innings. But in the fourth, Ryan Howard singled, took third on a double by Jayson Werth and scored on a groundout by Raul Ibanez.
Philadelphia got its second run in the seventh when Werth singled, went to third on Ross Gload's double and scored on Carlos Ruiz's groundout.
NOTES: The big lead gave Boston 2B Pedroia a chance to rest his painful right knee when manager Terry Francona removed him from the game in the top of the sixth. ... Moyer was 7-1 with Boston in 1996. ... Red Sox 1B Kevin Youkilis missed the game with back spasms. ... Jason Varitek's eighth-inning double gave the Red Sox eight in a game for the first time since Aug. 18, 2006, when they had eight against the New York Yankees. ... Moyer faced 13 batters and threw 61 pitches. In his previous start, a complete game 6-2 win over San Diego, he threw 98 pitches.
