Jankowski was an unrestricted free agent after the Calgary Flames opted not to give him a qualifying offer, which would have allowed them to retain his rights as a restricted free agent.
The 26-year-old center scored seven points (five goals, two assists) in 56 games with the Flames last season and no points in five postseason games.
Jankowski has scored seven shorthanded goals since becoming a full-time NHL player in 2017-18, which is tied for fifth among all players during that span.
"Mark is another versatile player that gives us an option at the center position," general manager Jim Rutherford said. "His added experience on the penalty kill, where he has had success over the last few seasons, makes him a good fit for our team."
Selected by Calgary in the first round (No. 21) of the 2012 NHL Draft, Jankowski has scored 64 points (36 goals, 28 assists) in 208 regular-season games and no points in 10 postseason games.
The Penguins also agreed to terms with unrestricted free agent forward
Evan Rodrigues
on a one-year, $700,000 contract.
The 27-year-old scored one goal in seven games last season with the Penguins, who acquired him in a trade with the Buffalo Sabres on Feb. 24. He scored 10 points (six goals, four assists) in 45 games for the Penguins and Sabres. Rodrigues did not play in Pittsburgh's four-game loss to the Montreal Canadiens in the Stanley Cup Qualifiers.
The Penguins traded Rodrigues to the Toronto Maple Leafs on Aug. 25 as part of the six-player deal that sent forward Kasperi Kapanen to Pittsburgh. Toronto did not give Rodrigues a qualifying offer, which would have allowed them to retain his rights as a restricted free agent.
"When you look at Evan Rodrigues, he was part of the Kapanen trade," Rutherford said. "That was because we knew we weren't going to qualify him and get caught up in arbitration. He worked his way back to us at a number we could fit [under the NHL salary] cap, so we're happy about that. We've always liked Evan as a player."
Rodrigues has scored 72 points (27 goals, 45 assists) in 199 NHL games with the Sabres and Penguins.
NHL.com independent correspondent Wes Crosby contributed to this report
