He is known for his roles as Casper Rose in the Sky One drama Dream Team (2005–2006) and Sean Slater in the BBC soap opera EastEnders (2006–2009, 2019, 2021, 2022).

[7] He made his acting debut in 2005, when he had a guest role in an episode of the CBBC children's programme The Basil Brush Show, playing a character named Sven Garley.

[14] On 13 November 2012, Kazinsky joined the cast of the sixth season of the fantasy drama series True Blood, which premiered in 2013.

[15] That same year, Kazinsky appeared in Guillermo del Toro's science-fiction monster film Pacific Rim, as Chuck Hansen, an Australian Jaeger pilot.

[17] His character, Jimmy Pritchard, was a murdered elderly ex-cop who is genetically brought back to life as a man in his mid-30s with unusual powers.

[19] Kazinsky co-starred as Orgrim Doomhammer in the fantasy adventure film Warcraft, based on the video game of the same name which was released in May 2016.

[20][21] An avid World of Warcraft player, Kazinsky credits the game with giving him self-confidence during a period in which he would be harassed and attacked by people who confused him for the Sean Slater character.