Sokolov, 20, has spent the previous three seasons with the Cape Breton Screaming Eagles. The Russian sniper led the Quebec Major Junior Hockey League with 46 goals and finished third with 99 points in 2019-20 after going undrafted in his first two years of eligibility.
"To Egor's credit, he's worked especially hard for this," Senators general manager Pierre Dorion said. "Despite initially being undrafted, he applied himself to improve many facets of his game to the point where he led the Quebec league in goals last season. We were pleased to be able to select him where we did last month and look forward to seeing his career progress."
Sokolov signed a professional tryout contract with the Columbus Blue Jackets in September 2019, but was released by the club after appearing in one preseason game.
The 6-foot-4 winger also represnted Russia at the 2020 world juniors, contributing three goals and one assist through seven contests.
Sokolov was selected by Ottawa in the second round (61st overall) of the 2020 NHL Draft.