On 14 July 2017, Gusev signed a two-year contract extension with Kontinental Hockey League (KHL) powerhouse club SKA Saint Petersburg.

He continued his offensive dominance in the post-season, contributing 19 points in 18 games before suffering a conference final defeat for the second consecutive season to CSKA Moscow.

On 9 April 2021, the Devils placed Gusev on unconditional waivers in order to mutually terminate the remainder of his contract.

[7] As a free agent over the summer and approaching the 2021–22 season, Gusev opted to continue his career in the NHL, signing a Professional Tryout contract in accepting an invitation to attend the Toronto Maple Leafs training camp on September 18, 2021.

[10] On 18 July 2023, Gusev as a free agent agreed to terms on a one-year contract with his fifth KHL club, HC Dynamo Moscow, for the 2023–24 season.