[5] Emnes made his debut for Sparta Rotterdam in the 2005–06 season, which came on 11 December 2005, coming on as a late substitute, in a 3–2 loss against RKC Waalwijk.

[17] He later scored his eighth goal of the season against SC Heerenveen on 13 April 2008, resulting 4–2 win against Sparta Rotterdam and helping the side avoid relegation.

[18] For his performance as a result of scoring eight goals in twenty–nine appearances in all competitions, Emnes was declared Sparta Fans' Player of the Year.

[19] Following this, Emnes was linked a move away from Sparta Rotterdam, with top Netherlands clubs, such as, Feyenoord, AFC Ajax and SC Heerenveen were interested in signing him.

[22] Upon joining the club, Manager Gareth Southgate said: "He can play anywhere along the front line, so he has versatility to go with pace, energy and technical skills.

[24] It was not until on 25 October 2008 when Emnes made his league debut for the club, coming on as a late substitute, in a 1–1 draw against Blackburn Rovers.

[25] However, his first team opportunities at the club became limited, due to strong competitions in the forward position and as a result, Emnes had his playing time restricted, mostly coming on from the substitute bench.

[37][38] After his loan spell at Swansea City came to an end, Emnes made his first Middlesbrough's appearance of the season, coming on as a 59th-minute substitute, in a 1–0 loss against Millwall on 20 November 2010.

[39][40] He regained his first team place under the management of Tony Mowbray and continued his partnership with Leroy Lita and Scott McDonald.

[47] After serving a three match suspension, Emnes returned to the starting line–up against Hull City on 23 April 2011 and set up two goals for Scott McDonald, who scored a hat–trick, in a 4–2 win,[48] Ahead of the 2011–12 season, Emnes and strike partner Leroy Lita were linked with a transfer to Swansea City for a combined fee of £4 million, a move which Lita made.

[56] Emnes scored the only goal in an away victory at Crystal Palace on 17 September 2011, a win which put Middlesbrough top of the Championship table.

[61] Throughout the 2011–12 season, Emnes continued to be in a first team regular for the side, forming a partnership with McDonald and Bartholomew Ogbeche.

[67] However, during a 2–1 win against Bolton Wanderers on 29 October 2012, he suffered a hamstring injury in the 22nd minute and was substituted, leading him to be sidelined for a week.

[75] However, following a 2–1 loss against Accrington Stanley in the first round of the League Cup, he was booed by the club's supporters, which led Manager Tony Mowbray defending him.

[78] After missing out three matches, he made his return to the starting line–up, setting up the club's third goal of the game, in a 4–1 win against Yeovil Town on 5 October 2013.

[81] On 23 October 2010, Emnes scored his second league goal in English football, finding the net during his Swansea debut against Leicester City after coming on as a half-time substitute for Stephen Dobbie.

[82] On 7 November, Emnes scored a second goal for Swansea in the 156th South Wales derby, a strike which turned out to be enough to see off local rivals Cardiff City in a 1–0 win for the Swans.

[86] Emnes made his first appearance for the club in four years, starting the match before being substituted at half–time, in a 3–0 win against rivals’ Cardiff City on 8 February 2014.

[87] He then played in both legs of the UEFA Europa League Round of 32 against Napoli, losing 3–1 on aggregate and resulting in Swansea City's elimination from the tournament.

[92] Emnes’ first game after signing for the club on a permanent basis came on 20 September 2014, coming on as a late substitute, in a 1–0 loss against Southampton.

[93] Three days later on 23 September 2014, Emnes scored his first competitive goal for Swansea, on his return, in a 3–0 home win over Everton in the League Cup.

[95] However, Emnes found himself behind the pecking order in the striker position and placed on the substitute bench, as well as, his own injury concern.

[97] At the start of the 2015–16 season, Emnes scored his first goal in his first appearance, which came in the first round of the League Cup, in a 3–0 win against York City.

[99] It was not until on 28 December 2015 when Emnes made his first league appearance of the season, making a start and played for 56 minutes before being substituted, in a 0–0 draw against Crystal Palace.

[101] After making one appearance for Swansea City in the 2016–17 season, it was announced on 31 August 2016 that Emnes signed a loan for Football League Championship side Blackburn Rovers until 15 January 2017.

[102] Emnes made his Blackburn Rovers debut on 10 September 2016, coming on as a 77th-minute substitute, in a 1–1 draw against Queens Park Rangers.

[106] However, during a 1–0 loss against Sheffield Wednesday on 27 September 2016, Emnes had a goal wrongly disallowed when "Danny Graham was adjudged to have been in an offside position.

[112] Despite facing criticism for his lack of goals and can go missing in matches, Emnes continued to be involved in the first team until his loan spell at Blackburn Rovers ended on 15 January 2017.

[123] A month later on 24 October 2017, he set up two goals for Ioan Hora, who scored a hat–trick, in a 6–0 win against Erzincanspor in the fourth round of Türkiye Kupası.

[128] On 6 September 2018, Emnes joined Major League Soccer side Vancouver Whitecaps FC[129] after receiving offers from clubs in China, England, the United States, and Italy.