2005-06: Denis Kazionov split the season between HC MVD in the Russian Super League and Tver in the Russian Third division. He had 1 assist with 12 PIM in 26 games with MVD and scored 6 goals with 13 assists and 34 PIM in 31 games for Tver.
2006-07: Kazionov scored his first two Russian Super League goals during his 24-game stint with HC MVD and again saw time in both the RSL and the Third division with Tver. Kazionov also had an assist with 8 PIM for the HC MVD and was scoreless with 2 PIM in two playoff games. Kazionov was dominant in the third level for Tver, scoring 23 goals with 15 assists and 42 PIM in 13 games.
2007-08: Kazionov began the season with Metallurg but failed to establish a full-time spot after going scoreless in eight games. He then ended up with Avangard Omsk where for the third year in a row he split the season between the RSL and the Third Division. Kazionov scored 10 goals with 6 assists and 16 PIM in 13 games for Avangard's third division club but could not parlay that success into a regular role with the RSL club. He played 18 games with Avangard Omsk in the RSL to finish the season but failed to register a point and had 4 PIM.
2008-09: Kazionov started the season with Amur Khabarovsk in hopes of finally establishing himself in the newly-christened KHL but ended up spending the majority of the season in the Czech Republic. After being scoreless with 6 PIM and seeing very little ice time with Amur, he joined BK Mlada Boleslav in the Czech Elite League. Kazionov scored 4 goals with 6 assists in 33 games with BK Mlada and had a whopping 99 PIM.
2009-10: Kazionov established himself in a full-time role in his fifth year of pro hockey. Playing for first-year KHL club Automobilist Ekaterinburg, Kazionov scored 5 goals with 4 assists and was -18 with 20 PIM in 51 games. Ekaterinburg finished 19th in the 24-team league. In four playoff games, Kazionov was scoreless and -3 with 6 PIM. Kazionov signed a KHL contract with HK Atlant in May.
2010-11: Kazionov appeared in seven KHL contests with two different clubs while skating for Izhstal Izhevsk in the VHL (Russian Second League) for most of the season. Kazionov's only KHL point, an assist, came during his four-game stint with Metallurg Novokuznetsk. In three games with Traktor Chelyabinsk he had no points or penalties and was -1. In 33 games with Izhstal, Kazionov scored 10 goals with 7 assists on a team that finished last in the East Division.
2011-12: Kazionov saw his most extensive KHL action since the 2009-10 season; appearing in 47 games for Yekaterinburg Avtomobilst. He led the team with 81 penalty minutes and scored 3 goals with 6 assists; finishing with a minus-18 plus/minus. Avtomobolist finished last in the Kharlamov Division.
Kazionov is a player with average skills who is big and plays with a lot of energy. The younger brother of 2002 Lightning draft pick Dmitri Kazionov, he is also a product of the Dynamo Moscow youth system. However, while Dmitri is more of a gifted scorer and has played on two championship teams with Kazan Ak Bars, the younger Kazionov is more of a checking forward who creates opportunities with his physical play and is a tough player on the forecheck.