On 27 June 2009, Silfverberg was drafted by the Ottawa Senators in the second round of the 2009 NHL Entry Draft, 39th overall. On 30 May 2011, he signed a three-year, entry-level contract with Ottawa, though he elected to return to Sweden and continue to play for Brynäs IF for the 2011–12 season rather than to make the move to North America. Silfverberg was named the winner of the Guldhjälmen award as the most valuable player, as voted by the players in the Elitserien, for the 2011–12 regular season, as well as the Guldpucken as player of the year. He finished the regular season with 24 goals and 54 points in 49 games, ranking second in the Elitserien scoring race behind Robert Rosén of AIK IF, who scored 21 goals and 39 assists for 60 points. Silfverberg's point totals represented a 20-point jump from his totals in the 2010–11 campaign, in which he registered 34 points. Silfverberg's offensive success continued in the Elitserien playoffs, and his production was a large factor in Brynäs' eventual Swedish championship title, scoring 13 goals and seven assists for 20 points. His 13 goals set a new record for total goals scored by a single player in the playoffs, surpassing Daniel Alfredsson's previous record of 12 goals set in the 2004–05 season. Ultimately, Silfverberg was also awarded the Stefan Liv Memorial Trophy as the MVP of the playoffs. During the semi-finals, Silfverberg took over the role as the captain of Brynäs, following Andreas Dackell's retirement. He also wore the number 100 on his jersey during the second half of the season, in honor of Brynäs' 100th anniversary. After the Elitserien playoffs concluded, Silfverberg joined the Ottawa Senators for their run in the 2012 Stanley Cup playoffs. He made his NHL, as well as his Stanley Cup playoff, debut on 23 April 2012, in Game 6 of the Eastern Conference Quarter-final series against the New York Rangers. Registering nine minutes of ice time, Silfverberg recorded one shot on goal in the Senators' 3–2 loss. The Senators were eliminated from the playoffs in Game 7 of the series. In the second Senators game after the resolution of the 2012–13 NHL lockout, Silfverberg scored his first career NHL goal on 21 January 2013, against José Théodore of the Florida Panthers. On 5 July 2013, Silfverberg was traded to the Anaheim Ducks, along with forward Stefan Noesen and a first-round draft pick in 2014, in exchange for forward Bobby Ryan. On 15 August 2014, the Ducks announced they had re-signed Silfverberg as a restricted free agent to a one-year, $850,000 contract. On 7 August 2015, the Ducks signed Silfverberg a four-year contract extending until the 2018–19 season with an annual salary cap of $3.75 million.
