The major leagues' leading hitter, Arraez hit three doubles and two singles to raise his average to .390. He joins Justin Turner in 2017 as the only players over the past 10 years to be batting .390 or better at least 200 at-bats into a season, according to ESPN Stats & Information research. Turner, who was batting .390 through 205 at-bats, finished that season with a .294 average.
A day after going 0-for-4 in the series opener, Arraez also became the first player in franchise history with five hits and five RBIs in a game.
"When I was a kid yes, but I've never had five hits," Arraez said.
In addition to going hitless Friday, Arraez had additional motivation. Arraez and his wife, who is expecting the couple's third child, learned in a gender reveal that they will have their third girl.
"It's emotional and because of that I have to play well," Arraez said. "I'm going to do everything possible that my girls have beautiful lives."
Joey Wendle doubled twice and singled for the Marlins, who finished with 14 hits.
The A's dropped to a major league-worst 12-48 and lost their 13th straight on the road.
Rookie Eury Perez threw five scoreless innings of four-hit ball in his fifth major league start. The 20-year-old Perez (3-1) struck out five and walked one. George Soriano got the last nine outs for his first major league save.
"I feel very confident when I am in the game and the support I get from my teammates also helps a lot," Perez said. "It gives me a lot of energy to go out on the mound and perform."
The Marlins struck early against Oakland starter Luis Medina with a four-run second. Jonathan Davis hit a two-run double and scored on Arraez's single. Jorge Soler's single advanced Arraez to third before Bryan De La Cruz had a sacrifice fly to right.
Consecutive walks to Jean Segura and Nick Fortes in the third ended Medina's outing. Wendle followed with a single against reliever Sam Long to load the bases. Arraez's one-out double to left-center cleared the bases and put Miami ahead 7-0.
"I feel like I keep saying that but it's freaking June already and he's still doing it," Marlins manager Skip Schumaker said of Arraez. "It's surprising I guess because it's already June and he's hitting like .390 but with the work he puts in, it's not surprising because of how relentless he is."
Medina (0-5) gave up six runs and six hits, walked four and struck out two.
Arraez's RBI double and De La Cruz's second sacrifice fly in the fifth padded the lead.
Shea Langeliers' RBI single in the eighth put Oakland on the board and snapped an 18-inning scoreless string.
"Offensively, we don't string hits together consistently," A's manager Mark Kotsay said. "Later in the game, I thought we had better at-bats than we did earlier. You focus on those better at-bats and prepare for [Sunday]."
With the lopsided lead, the Marlins pinch-hit for Arraez with Garrett Hampson in the eighth.
The Associated Press contributed to this story.