It was Martinez who provided the dagger in the fifth inning, lining a three-run shot into the right-field stands to break a 2-2 tie.
Ian Kinsler started the rally with a one-out single, then Torii Hunter followed by hitting a high chopper to third base. Kyle Seager wanted to go to second, but dropped the ball, then quickly gathered it and fired to first.
Hunter was initially ruled safe on a bang-bang play, but an instant-replay review overturned the call.
"I was trying to hurry to get it to [second baseman Nick] Franklin," Seager said. "I know Hunter runs well but [I wanted to] at least give him a shot at the double play and we get out of that inning. It's a play that I'd definitely like to get over there. I don't know what happened… I just missed it and it got out of my glove."
With first base open and two outs, McClendon opted to intentionally walk Cabrera, who hit a long two-run homer that gave the Tigers a 2-0 lead in his previous at-bat in the third.
Martinez answered by knocking starter Hisashi Iwakuma's 2-2 slider into the first row of seats in right field.
"I was trying to win a game. It's that simple," McClendon said of why he opted to give Cabrera (.328 batting average) a free pass. "It didn't work. We didn't execute. Move on."
Martinez's home run came on the 10th pitch of the at-bat. The pitch was not where Iwakuma wanted it.
"He kept fouling off pitches," Iwakuma said through translator Antony Suzuki. "At one point I thought that I would get this guy out, but I hung a slider and he took advantage of it."
That was all Detroit needed on a night ace pitcher Justin Verlander was dealing and the Mariners were without No. 3-hitting second baseman Robinson Cano (minor hand injury).
Seager tied the game at 2 in the fourth by crushing a two-run homer that landed deep into the right-field seats after Justin Smoak drew a one-out walk. It was Seager's second home run in as many nights and his team-high eighth dinger of the season. All have come at Safeco Field.
He also lined a double in the second and finished 2-for-4 with a run scored and two RBIs. In his last 32 games, Seager is hitting .305 (36-for-118) with 31 RBIs, raising his batting average to .253.
Meanwhile, Iwakuma suffered his second loss in a row, dropping to 3-2. The 33-year-old right-hander gave up five runs on eight hits and two walks as his ERA jumped to 3.09. He struck out five and threw 98 pitches, 69 for strikes. Cabrera's third inning homer ended his stretch of 50 2/3 consecutive scoreless innings against the A.L. Central.
Iwakuma said the fastball Cabrera hit out was where he wanted it -- up and inside.
"I've pitched to him many times in the past and I've located that pitch there and gotten outs," he said. "But today he got to that pitch. You look at him. He's a monster."
Iwakuma was outdueled by Verlander, a fiery competitor who was undoubtedly perturbed with his last outing, when he gave up a career-high nine runs, six earned, in a loss to the Texas Rangers.
His redemption Friday came in the form of a five-hit, three-run performance over 7 2/3 innings. Appearing in control for most of the night, Verlander earned his sixth win of the season. He struck out seven and walked just one. Davis added the insurance with a solo shot in the seventh.
"He throws hard, he's got the big curveball and he mixes it up pretty good," Seager said of Verlander. "He definitely picks up the intensity when guys are in scoring position. It was kind of the normal from him."
The loss pushed the Mariners to 26-28 on the year and 4-5 on their season-high, 11-game homestand. It also pushed McClendon to 0-1 as Mariners manager against his former club.
"I'm glad this day's over and now we can get back to normalcy and hopefully getting back to winning ball games starting tomorrow," he said.