The two-way deal will run through the 2020-21 campaign.
Marino, 22, was acquired by the Penguins from Edmonton on July 26 in exchange for Pittsburgh's 2021 sixth-round draft choice. He was originally drafted by the Oilers in the sixth round (154th overall) of the 2015 NHL Draft.
"Adding a young defenseman like John to our organization will be very helpful," said Rutherford. "His development was accelerated last year and he became a top-10 defenseman in college hockey, giving himself a chance to play at the NHL level."
The 6-foot-1, 181-pound defenseman played three seasons collegiately for Harvard University of the ECAC Conference, where he tallied 42 points (7G-35A) in 101 career games. This past season, he dressed for 33 games, registering three goals and eight assists for 11 points.
In his freshman season in 2016-17, Marino helped the Crimson to an ECAC Championship and was also named to the NCAA All-Ivy League Second Team. The North Easton, Massachusetts native's best season with Harvard came during the 2017-18 campaign when he recorded 16 points (2G-14A) and a plus-21 in 33 games.
Prior to college, Marino played one season with the Tri-City Storm of the USHL in 2015-16, finishing second among team defensemen in goals (5), assists (25) and points (30) in 56 games. He also suited up for 11 playoff games, picking up two assists en route to Tri City's Clark Cup Championship.
