2006-07: In nine games with the KalPa U18 squad, Teemu Hartikainen tallied five goals and 11 points, adding another three points (2g+1a) in 11 games with the U20 team.
2007-08: Hartikainen appeared with three different KalPa squads this season. In seven games with the U18 squad, he netted a career-high nine goals and 15 points, adding another 17 points (10g+7a) in 37 games with the U20 KalPa team; he failed to register any points in his lone game with the KalPa SM-Liiga team. H also suited up for six games with the Finland National U18 team, netting two goals and three points at the WJC-18. Hartikainen was chosen in the sixth round, 163rd overall, of the 2008 NHL Draft by the Edmonton Oilers.
2008-09: The Finnish winger continued his hockey career within the KalPa system, appearing in his first full season with the teams SM-Liiga squad. In 51 games, he scored a career-high 23 points (17g+6a), taking the SM-Liiga Most Goals by Rookie and Rookie of the Year awards. He also potted another nine points (3g+6a) at the WJC with Team Finland.
2009-10: Hartikainen played a key role in the resurgence of his hometown KalPa Kuopio club as a 19-year-old in his second season in Finland's SM-Liiga. Playing alongside long-time NHL forward Sami Kapanen he scored 15 goals with 18 assists and was +6 with 22 PMs in 53 games as KalPa finished second in the league. In 12 playoff games, Hartikainen tied Kapanen for the team lead with six goals and had one assist as KalPa reached the second round. Hartikainen was the leading goal scorer for fifth-place Finland at the 2010 U20 World Junior Championship, scoring 4 goals with 2 assists, and finished -3 with 4 PMs in six games. He signed a three-year, entry-level contract with Edmonton in May 2010.
2010-11: Hartikainen made his NHL debut with the Oilers in March 2011 and skated in 12 NHL games after spending the majority of his first season in North America with the AHL's Oklahoma City Barons. He scored 3 goals with 2 assists and was -3 with 4 PMs, averaging 17 minutes of ice time with Edmonton. Hartikainen scored 17 goals with 25 assists and was -1 with 27 PMs in 66 games for Oklahoma City. He skated in all six playoff games with the Barons and was -2 with 1 assist and 4 PMs.
2011-12: Hartikainen was returned to Edmonton's AHL affiliate Oklahoma City following the Oilers' camp. He was recalled by the Oilers at the beginning of January and appeared in five games before being returned to the Barons. He was recalled again in March before joining the Barons for the AHL playoffs. He scored 2 goals with 3 assists and was plus-one with 6 penalty minutes, averaging 13 minutes of ice time, in 17 games with the Oilers. He was off to a fast start for Oklahoma City before suffering a shoulder injury in November which kept him out until December 27th. He scored 14 goals with 18 assists in 51 games for the Barons and was plus-one with 19 penalty minutes. He scored five goals on the power play. Oklahoma City finished first in the West Division and reached the playoff semifinals. Hartikainen scored 4 goals with 4 assists and was plus-one with 4 penalty minutes in 14 penalty games.
2012-13: Hartikainen played in 23 games with Edmonton in his third season with the Oilers organization and was one of the top scorers for AHL affiliate Oklahoma City. He scored 1 goal with 2 assists and was -8 with 6 penalty minutes; averaging 10:34 minutes of ice time for the Oilers. In 47 regular season AHL games he scored 14 goals with 23 assists and was +6 with 23 penalty minutes. The Barons finished third in the South Division and reached the Western Conference finals. Hartikainen was the team's third-leading scorer in the playoffs with 7 goals and 8 assists in 17 games and was +10 with 6 penalty minutes. He was tendered a qualifying offer by the Oilers, becoming a restricted free agent. In June 2013 he signed to play for Salavat Yulaev in the KHL in 2013-14.
Hartikainen is known for his leadership as well as gritty and physical play. He has good size and his willingness to get his hands dirty endears him to teammates, coaches, and fans alike. Often described as a Tomas Holmstrom-type player for the way he battles all over the ice, especially in the corners and in front of the net, he is suited to play any number or roles on a team. His skating has long been described somewhere between ‘lacking’ and ‘atrocious,’ however it has improved immensely in the last couple years.
Hartikainen has improved by leaps and bounds since being drafted, and there is a real chance his ceiling could be as high as a top six forward when all is said and done. In the near term however, he will likely make his living in a bottom six role, where his endless energy and physical style of play will make him an effective player and a pain to play against. After becoming a restricted free agent in July 2013 and receiving a qualifying offer from Edmonton, Hartikainen made the decision to sign with Ufa of the KHL for the 2013-14 season.
Hartikainen and Cameron Abney were dealt in January of 2014 by the Edmonton Oilers to the Toronto Maple Leafs in exchange for Mark Fraser.