After his draft selection to the Maple Leafs, Valiev was promptly signed to a three-year entry-level contract on July 10, 2014.[3] Following his second season within the Kootenay Ice organization of the Western Hockey League, Valiev made his professional debut after the 2014–15 season, playing in 2 games with the Maple Leafs AHL affiliate, the Toronto Marlies.
During the 2015–16 season, behind the back of enjoying a solid season in his return to the Marlies, Valiev received his first NHL recall on March 11, 2016.[4] He made his NHL debut with the Maple Leafs in a 4–0 defeat to the Ottawa Senators on March 12, 2016.[5]
On February 25, 2018, one day before the trade deadline, Valiev was traded by the Maple Leafs, alongside teammate Kerby Rychel and a second-round pick in 2018 NHL Entry Draft to the Montreal Canadiens in exchange for Tomáš Plekanec and minor league forward Kyle Baun.[6] On May 31, Valiev signed a one-year, two-way contract extension with the Canadiens.[7]
Following two seasons within the Flames organization assigned to AHL affiliate, the Stockton Heat, Valiev sat out the shortened and pandemic-delayed 2020–21 season as a free agent.
On 5 July 2021, Valiev returned to the professional ranks in securing a try-out contract with his original Russian club, Ak Bars Kazan of the KHL.[9] After a successful pre-season, Valiev secured a one-year contract for the 2021–22 season with Ak Bars on 26 August 2021.[10] Valiev made one appearance with Ak Bars, playing the majority of his contract with VHL club, Bars Kazan, before he was traded to Belarusian KHL club, HC Dinamo Minsk, in exchange for the rights to Julius Honka on 27 December 2021.[11]
On 5 July 2022, Valiev continued his tenure in the KHL, joining Admiral Vladivostok on a two-year contract.[12]
