Ruiz also had an RBI double during a four-run fourth inning that helped the NL East leaders turn this one into a rout.
Rodrigo Lopez allowed one run over six innings to give the Phillies their 13th win in their last 14 games.
The Phillies are on their longest winning streak since 2006 and improved to 23-23 at home. They were 13-22 at home before they went 9-1 in their last homestand.
Ted Lilly was rocked in his shortest outing of the season for the Cubs, who snapped a four-game winning streak.
The teams boasted the two longest winning streaks in the National League, but the start of the anticipated three-game series was all Phillies.
With Jack Nicholson wearing a Yankees cap and watching from a front-row seat, the Phillies wasted no time picking up where they left off in their first game back in Philadelphia since before the All-Star break.
Jimmy Rollins led off the game with a single, Shane Victorino followed with a double, and Ibanez connected off Lilly two batters later for his 25th homer, well over the 401-foot sign in dead center.
Ibanez moved into second place in the NL in homers, and Howard is right behind him with 24. Howard's solo shot in the eighth made it 10-1.
Chad Durbin tossed three scoreless innings to finish off the win and earn his first save for the hottest team in baseball.
Lilly had pitched at least six innings in 14 straight starts and had allowed only six runs in his last three outings. The All-Star lefty gave up five runs after two -- Ruiz connected for a two-run shot in the second -- then completely unraveled behind a defensive gaffe in the fourth.
Ruiz's double and Rollins' sacrifice fly stretched the lead to 7-0. Victorino hit a deep fly to the warning track in left, and the ball bounced off the heel of Alfonso Soriano's mitt and onto the dirt for an error and another run scored.
The catch would have ended the inning. Instead, Chase Utley followed with an RBI single for a 9-0 lead that capped the inning.
Two of the runs charged to Lilly in the inning were unearned. He gave up nine runs and eight hits in four innings.
Lopez, who left his last start with right shoulder inflammation, never let the Cubs rally.
His solid effort helped his cause to stay in the rotation once Pedro Martinez is deemed healthy enough to join the Phillies. Martinez, signed as a free agent last week, was medically cleared to pitch a simulated game on Tuesday and might take Lopez's turn in the rotation in August. More effective outings like this one and Lopez could make Philadelphia's decision a tough one.
Ryan Theriot's RBI single in the fifth was all the Cubs got off Lopez.