[4] Having been called up to the first team on two occasions, on 24 February 2005 Emanuelson made his Ajax debut, coming on as a 79th-minute substitute, in a 3–1 loss against Auxerre in the second leg of the UEFA Cup Round of 32.

In the play-offs, they defeated Feyenoord but lost to FC Groningen in the club's unsuccessful attempt to claim a spot in the Champions League preliminaries for the following season.

At the start of the 2006–07 season, Emanuelson played the whole game, as Ajax beat PSV Eindhoven 3–1 to win the Johan Cruyff Shield.

[25] However, Emanuelson played in both legs of the third round of the UEFA Champions League against Copenhagen, as the club were eliminated following a 4–1 defeat on aggregate.

[36] Emanuelson was featured in the KNVB Cup Final against AZ, playing 120 minutes and finishing 1–1 as Ajax went on to lose 8–7 as a result and win the tournament for the second time in a row.

At the start of the 2007–08 season, Emanuelson played the whole game, as Ajax beat PSV Eindhoven 1–0 to win the Johan Cruyff Shield with the former won for the third consecutive year.

[46] By February, Emanuelson began primarily played as a left midfielder because of his weak defending abilities and Jan Vertonghen took over the position.

[49] However, he eventually played in the left–back position against SC Heerenveen in play–offs for the UEFA Champions League spot, as Ajax won 5–2 on aggregate.

[69] He played in both legs of the UEFA Europa League Play-off round against Slovan Bratislava, as the club won 7–1 on aggregate.

[78] He started in the 2009–10 Dutch Cup final against rivals, Feyenoord, and set up the second goal of the game for Siem de Jong, who scored twice to help the club to make it 2–0 in the first leg.

[79] In the return leg, Emanuelson helped Ajax beat Feyenoord, 4–1, winning the KNVB Cup for the third time in his career.

[92] On 23 January 2011, Italian Serie A club AC Milan announced the signing of Emanuelson on a three-and-a-half-year contract for a transfer fee of around €1.7 million.

[94] Emanuelson made his debut for the club on 26 January 2011 in a Coppa Italia match against Sampdoria, providing an assist for Alexandre Pato.

[102] He then helped AC Milan qualify for the UEFA Champions League knockout stage after drawing 2–2 against Viktoria Plzeň.

[113] Since returning from a loan spell from the previous season, Emanuelson continued to establish himself in the left–back position, though he faced competition from Kévin Constant.

[140] Four days later after signing for the club on 6 January 2016, he made his Hellas Verona debut, coming on as a 62nd-minute substitute, in a 3–0 loss against Juventus.

After being released by Verona in the summer 2016, Emanuelson joined English Championship side Sheffield Wednesday on 6 September on a free transfer.

[150] Emanuelson made his FC Utrecht debut, coming on as an 80th-minute substitute, in a 0–0 draw against Valletta in the first leg of the UEFA Europa League Second Round.

[152] Emanuelson then played four times in the UEFA Europa League Qualifying Stage, where FC Utrecht reached the play–off round, only to lose against Zenit Saint Petersburg following a 2–1 loss on aggregate.

[158] In the Play–Off Round, Emanuelson played three times as the club were unsuccessful of earning a spot in the UEFA Europa League following a 5–3 aggregate defeat to Vitesse.

[160] He started out well, appearing in the first five league matches of the season and even scored his first goal for FC Utrecht, in a 1–1 draw against Fortuna Sittard on 1 September 2018.

[168] Two weeks later on 3 February 2019 against PEC Zwolle, Emanuelson set up FC Utrecht's second goal of the game before being sent–off in the 71st minute for a professional foul, in a 4–3 loss.

[170] Despite being further sidelined towards the end of the 2018–19 season, Emanuelson played once in the play-offs for the UEFA Europa League spot, as the club went on qualify for European football following a 3–1 win against Vitesse on aggregate.

At the start of the 2019–20 season, Emanuelson played in both legs of the UEFA Europa League Second Round match against HŠK Zrinjski Mostar, as FC Utrecht lost 3–1 on aggregate.

[193] He played four times at the major tournament in the 2008 Summer Olympics where the team was eliminated in the quarter-finals by eventual winners Argentina.

[196] In September 2005, Manager Marco van Basten called up to the Netherlands team for the first time as part of the preliminary selection but did not make the cut.

[198] On 16 August 2006, Emanuelson made his debut for the Netherlands senior team in a friendly match against the Republic of Ireland, as they won 4–0.

[202] Emanuelson then played the last 13 minutes of the game against Luxembourg on 17 November 2007, as the national side won 1–0 to qualify for the UEFA Euro 2008.

[204] Although Emanuelson hasn't been called up to the national team for two years, he hope his performance would earn him a spot in the World Cup.

His older brother Julian Emanuelson, also a product of the Ajax Youth Academy, played professionally for HFC Haarlem, and for Lustenau in Austria.