Zub was set to become a restricted free agent this off-season. Ottawa signed Zub to a one-year, entry-level deal last May after he put 13 goals, nine assists and 22 points in 57 games with the KHL’s SKA St. Petersburg in 2019-20.
The Senators kept Zub out of the lineup for the first eight games of the 2020-21 NHL season, but he became a fixture after playing his first NHL game January 31 against the Edmonton Oilers, missing only one game from that point on.
The 25-year-old put up 14 points and averaged 18:23 minutes of ice-time as a rookie in the NHL this season.
Ottawa forwards Brady Tkachuk and Drake Batherson, defenceman Victor Mete and goaltender Filip Gustavsson remain as notable restricted free agents for the Senators.
Sportsnet’s Elliotte Friedman reported on Wednesday that, along with Zub, the Senators were “grinding away” at an extension for Mete.