Larkin scored on a breakaway and Mrazek made 22 saves in the Red Wings 1-0 victory on Monday night.
Mrazek, appearing in an eighth straight game, earned his second shutout of the season and seventh of his career.
Cory Schneider stopped 20 for the Devils, who saw their three-game winning streak snapped.
Larkin provided the early theatrics, scoring on a nifty backhander to polish off the breakaway at 9:20 of the first period. Brad Richards hit Larkin with a long lead pass as Larkin slipped behind the Devils' defense and deked Schneider down to the ice. It was the 14th goal for Larkin, tops among rookies.
"We kind of crossed in our own zone and there wasn't much room for that pass to land," Larkin said. "I just flew. I got my head up quick."
From there it was a one-on-one showdown with Schneider.
"I saw he was out pretty far," the 19-year-old said. "He bit on the move, so I got pretty lucky there. It happened so fast, and it turned out to be a big goal."
As it turned out, the only goal and all the margin Mrazek and the Red Wings needed.
Detroit played an excellent defensive road game, limiting the Devils to only five shots in each of the second and third periods.
"The third period was probably the best period we played," Mrazek said. "We didn't give them many chances or good looks. We did a great job stick-on-stick, body on body. We didn't give many opportunities to score a goal."
The Devils came close to pulling even in the final minute of the opening period when Mrazek could not control Jiri Tlusty's rebound. It was loose in the crease, setting off a scramble before Mrazek covered the puck.
"They did a good job after the first," Schneider said. "Mrazek made some big saves early but after that, he was able to find pucks. He played well. He made the saves he had to make. We had some toward the net that just went wide, that just didn't have eyes.'
Detroit threatened to break the game open in the second period.
"I think it kind of got me in the elbow," Schneider said. "I got a little desperate. Sometimes you get lucky and they hit you."
Schneider got lucky several minutes later when Darren Helm hammered a shot off the crossbar, keeping Red Wings lead at 1-0.
The Devils, looking for another victory to solidify their playoff position, took some satisfaction in the effort but not the result.
"It was a hard-fought game by both teams," Devils coach John Hynes said. "I really liked the way we competed tonight from start to finish."
Mike Cammalleri, the Devils' leading scorer, missed a second straight game with an upper body injury. ... This was second of a six-game road trip that started with a 4-3 win in Buffalo. ... The Devils gave fans Schneider bobble-head dolls. . It was Detroit's second victory following a three-game losing streak.