Bruce and Izturis each had two hits, while Bruce scored four runs and Jack Hannahan was 3-for-4 with two RBI and two runs scored for the Reds, who rebounded from Friday's 4-2 loss in the opener.
Mat Latos (8-2) gave up four runs on six hits with four walks and 11 strikeouts over six innings for the win. He also added a two-run double at the plate.
"After putting us in that hole it was a big relief to me that the guys backed me up and put up some runs," said Latos.
Kyle Seager hit a two-run home run and drove in three for the Mariners, who had won three of four coming in. Jeremy Bonderman (1-3) was handed the loss as he gave up six runs on seven hits in five innings of work.
"He just had trouble getting through innings," said Seattle manager Eric Wedge about Bonderman. "You know, all those two-out RBIs they got tonight really killed us."
As in Friday's game, the Mariners jumped out to a 2-0 lead in the first inning as Endy Chavez singled with one out and Seager followed with his 13th homer of the year, a blast to right field.
The Reds got one back in the second as Bruce walked, took second on a wild pitch and later scored on an Izturis single to make it a 2-1 contest.
Seattle, though, got the run back in the third on a sacrifice fly from Seager that plated Brad Miller.
Cincinnati went on top for the first time in the series in the fourth inning. With one out, Hannahan doubled and Ryan Hanigan was issued a free pass with two outs. Latos, though, made the Mariners pay as he laced a double to the gap in right-center to tie the game. Shin-Soo Choo then plated Latos with a single to center for a 4-3 lead.
The Reds adder to their lead in the fifth as Izturis punched a double to right-center to bring home two runs for a 6-3 advantage.
Ryan drove in Dustin Ackley with a double in the sixth, but Bruce hit a two- run double in the home half and scored when Hannahan followed with a single for a 9-4 lead.
The Reds put the game away in the eighth as Brandon Phillips hit a sacrifice fly and Bruce followed with a fielder's choice to score another run. Hannahan then singled home a run and Ryan Hanigan's RBI double made it a 13-4 game.
Seager extended his hitting streak to seven games ... Seattle pitchers Felix Hernandez and Hisashi Iwakuma were named to the All-Star game on Saturday, while Reds first baseman Joey Votto and second baseman Brandon Phillips were named starters and will be joined by pitcher Aroldis Chapman ... Seattle was 0-for-11 with runners in scoring position and stranded 11 runners ... It was just the second win in 11 games against the Mariners for the Reds.
07/06 22:36:25 ET