Plotnikov was not drafted by any
NHL team. On 1 July 2015, Plotnikov bought out the final year of his contract with
Lokomotiv Yaroslavl. He signed a one-year, entry-level contract with the NHL's
Pittsburgh Penguins. In his first North American season in
2015–16, Plotnikov scored just two points in 32 games. From December 2015, he was a healthy scratch for almost two months. Displeased with his lack of playing time, Plotnikov requested a trade and was subsequently traded to the
Arizona Coyotes on 29 February 2016 in exchange for
Matthias Plachta and a conditional seventh-round draft pick in
2016, dependent on if the Coyotes resigned him. Plotnikov's struggles continued with the Coyotes, unable to find his offensive touch with one assist from 13 games. As a free agent from the Coyotes and with little success in the NHL, Plotnikov returned to Russia in agreeing to a two-year KHL contract with
SKA Saint Petersburg on 1 July 2016. Following his fourth season with SKA Saint Petersburg in the
2019–20 season, in which he served as team captain, Plotnikov was traded to his original club, Amur Khabarovsk in exchange for
Igor Rudenkov on 16 May 2020. Unable to agree to terms with Amur, Plotnikov was soon traded for the second time within the month, dealt to Metallurg Magnitogorsk in exchange for four prospects and financial compensation. He was then signed to a two-year contract on 28 May 2020. Following a lone season with Metallurg Magnitogorsk, Plotnikov left the club with a year remaining on his contract in agreeing to a one-year deal with fellow KHL club,
HC CSKA Moscow, on 6 July 2021. During his three season tenure with CSKA Moscow, Plotnikov captured two
Gagarin Cup championships, before leaving as a free agent and signing a four-year contract to return to former club SKA Saint Petersburg on 24 May 2024. ==International play==