Upon making his NHL debut on 19 January 2013, Rakel became the sixth youngest player to appear in a game for the Ducks at 19 years, eight months and 14 days.

He also helped the Ducks set a franchise record for most playoff power play goals with four during Game 5 of the team's first-round series against the Dallas Stars.

[23] Upon rejoining the Whalers, Rakell was named the OHL Player of the Week ending on 24 February after he accumulated six goals and three assists for nine points through four games.

[2] After attending the Ducks' 2013 training camp and preseason, Rakell was re-assigned to their American Hockey League (AHL) affiliate, the Norfolk Admirals, to begin the 2013–14 season.

[30] He shortly thereafter made his season debut and eventually tallied his first career NHL point, an assist, on 8 November 2013 in a game against the Buffalo Sabres.

[2] As the Ducks qualified for the 2014 Stanley Cup playoffs, Rakell made his postseason debut on 23 April for Game 4 of the Western Conference First Round against the Dallas Stars.

As he was a replacement for an injured Ryan Getzlaf, Rakell played on the Ducks' top line alongside Corey Perry and Emerson Etem.

[38] Due to injuries across the Ducks' lineup, Rakell made the teams' opening night roster for his first full rookie season at the NHL level.

[39] However, Rakell spent the majority of the season battling with fellow Swede William Karlsson for Anaheim’s fourth-line center spot.

[44] On 11 January, Rakell tied a franchise record for most points by a rookie in a single game after he tallied two goals and two assists in a 5–4 shootout win over the Winnipeg Jets.

[40] The Ducks and Rakell continued to find success, and they set a new franchise record in March for the all-time longest winning streak.

[46] As Rakell helped the Ducks qualify for the 2015 Stanley Cup playoffs,[47] he finished the regular season with nine goals and 22 assists in 71 games.

[40] During the Ducks' first-round matchup against the Winnipeg Jets, Rakell played on the third line alongside Andrew Cogliano and Kyle Palmieri.

However, as the season progressed, he began to see time on the Ducks' top line alongside Corey Perry and Ryan Getzlaf.

[3] In late November, Rakell was moved to the left wing of Getzlaf and Perry, and the trio immediately developed chemistry.

[51] On 24 November, Rakell and Perry scored two goals apiece and the trio combined for 10 points total in their 5–3 win over the Calgary Flames.

[52] Following the acquisition of David Perron in January, coach Bruce Boudreau chose to split up Getzlaf and Perry and reinvent the Ducks' top line.

[54] Rakell subsequently missed the remainder of the regular season following his appendectomy but returned to the lineup for Game 1 of the Western Conference First Round against the Nashville Predators.

[56] Once the Ducks were eliminated from playoff contention, Rakell was named as a replacement for Alexander Steen on Team Sweden at the 2016 World Cup of Hockey.

[57] He tallied one assist in 13:47 of ice time in a pretournament game before being forced to undergo further surgery to remove scar tissue from his stomach as a result of his appendectomy.

[64][65] On 15 January, Rakell scored his 18th goal of the 2016–17 season in his 200th career NHL game as the Ducks fell to the St. Louis Blues in overtime.

In the first round series against the Calgary Flames, Ducks coach Randy Carlyle placed Nate Thompson on Rakell's line with Corey Perry in Game 3.

He returned to the Ducks' lineup on 5 December with one shot on goal in 19:33 minutes of ice time in their 4–3 shootout loss to the Vegas Golden Knights.

[88] After struggling to score throughout the season, Rakell found success and chemistry with rookies Sam Steel and Jakob Silfverberg instead of his usual linemates Getzlaf and Perry.

[103] Although he would miss six games with a sprained wrist, Rakell returned to the lineup on 7 January ranked third on the Ducks in goals, points, and assists.

[106] He began the season on the Ducks' top line alongside Getzlaf and rookie Sonny Milano, although they only combined for one point through the first four games.

He subsequently earned praise from head coach Mike Sullivan who said: "He [Rakell] brings a skill element to that line [with Crosby and Guentzel] and an ability to create something out of nothing because of his talent level.

"[131] Following a 10-game goalless drought through late February and early March, Sullivan moved Rakell into a third line with Drew O'Connor and Mikael Granlund.

[134] He returned to Team Sweden again for the 2012 World Junior Ice Hockey Championships, where he scored two goals and three assists en route to a gold medal.

[137] Rakell made his senior debut at the 2018 IIHF World Championship, where he led Team Sweden to a gold medal.