In nine games with the KalPa U18 squad in 2006–07, the winger tallied five goals and 11 points, adding another three points (2g+1a) in 11 games with the U20 team. During the 2007–08 season, 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 drafted 163rd overall by the
Edmonton Oilers in the
2008 NHL entry draft. In 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. Hartikainen played three seasons in the
SM-liiga for
KalPa before joining the Oiler
American Hockey League affiliate, the
Oklahoma City Barons, for the
2010–11 AHL season. Hartikainen was named the AHL's Rookie of the Month in January 2011. On 14 March 2011, Hartikainen was recalled from the Oklahoma City Barons by the Oilers. On 17 March 2011, Hartikainen made his NHL debut in a 3–1 loss against the
Phoenix Coyotes, he recorded an assist on a third period power play goal by
Magnus Paajarvi. On 26 March, Hartikainen scored his first NHL goal against Calgary netminder
Miikka Kiprusoff in a 5-4 Shootout loss against the Calgary Flames. On 10 June 2013, after three years of attempting to make it on the Oilers' full-time roster, Hartikainen left the Oilers as he signed a contract in the Russian KHL with
Salavat Yulaev Ufa. On 31 January 2014, Hartikainen's NHL rights were traded by the Oilers to the
Toronto Maple Leafs in exchange for
Mark Fraser. In March 2022, Hartikainen left Salavat Yulaev after the first match the playoffs due to the
Russian invasion of Ukraine. ==Career statistics==