On 13 July 2011, Zibanejad signed a three-year, entry-level contract with the Ottawa Senators, the team that drafted him sixth overall in the 2011 NHL Entry Draft.
After an impressive training camp, Zibanejad joined the Senators for their first game of the 2011–12 season.
He registered his first career NHL point in his first game, an assist on a goal by Filip Kuba in a 5–3 loss to the Detroit Red Wings.
After just one point in nine games played, Zibanejad was reassigned to his most recent club, Djurgårdens IF, on 26 October.

In June 2012, Zibanejad was rumoured to be a key part of a package Ottawa was offering to the Columbus Blue Jackets in exchange for disgruntled superstar Rick Nash.
The offer was allegedly withdrawn when Columbus general manager Scott Howson informed the Senators Nash was unwilling to waive his no-trade clause to accept a move to Ottawa.

In August 2012, the Senators announced Zibanejad would spend the 2012–13 season in North America, either in the NHL with the Senators or with the club's American Hockey League (AHL) affiliate, the Binghamton Senators.
Due to the NHL lockout, Zibanejad began the season with Binghamton, where he registered 11 points in 23 games while battling injuries.
He was called up to Ottawa on 28 January 2013, and played in his first NHL game of the season on 29 January against the Washington Capitals, a game in which he was selected as the first star.
The following night, on 30 January in a game against the Montreal Canadiens, Zibanejad scored his first career NHL goal.
The goal came on the power play against goaltender Peter Budaj and with assists from Colin Greening and André Benoit.
In the 2015–16 season, Zibanejad scored a career high 21 goals with 30 assists.
On 13 July 2011, Zibanejad signed a three-year, entry-level contract with the Ottawa Senators, the team that drafted him sixth overall in the 2011 NHL Entry Draft. After an impressive training camp, Zibanejad joined the Senators for their first game of the 2011–12 season. He registered his first career NHL point in his first game, an assist on a goal by Filip Kuba in a 5–3 loss to the Detroit Red Wings. After just one point in nine games played, Zibanejad was reassigned to his most recent club, Djurgårdens IF, on 26 October.
In June 2012, Zibanejad was rumoured to be a key part of a package Ottawa was offering to the Columbus Blue Jackets in exchange for disgruntled superstar Rick Nash. The offer was allegedly withdrawn when Columbus general manager Scott Howson informed the Senators Nash was unwilling to waive his no-trade clause to accept a move to Ottawa.
In August 2012, the Senators announced Zibanejad would spend the 2012–13 season in North America, either in the NHL with the Senators or with the club's American Hockey League (AHL) affiliate, the Binghamton Senators. Due to the NHL lockout, Zibanejad began the season with Binghamton, where he registered 11 points in 23 games while battling injuries. He was called up to Ottawa on 28 January 2013, and played in his first NHL game of the season on 29 January against the Washington Capitals, a game in which he was selected as the first star. The following night, on 30 January in a game against the Montreal Canadiens, Zibanejad scored his first career NHL goal. The goal came on the power play against goaltender Peter Budaj and with assists from Colin Greening and André Benoit. In the 2015–16 season, Zibanejad scored a career high 21 goals with 30 assists.
Mika Zibanejad