The Germany international winger only agreed a new deal in December, but on Friday put pen to paper on fresh terms that will see him remain at the BayArena until June 2020.
Bellarabi has started every league game under Schmidt in 2014-15 and is the club's top scorer in the Bundesliga with nine goals, the best return of his career.
Chelsea and Liverpool had both been linked with a move for the 24-year-old after impressing in a season that has also seen him make his international debut in October.
However, he has shunned those advances and hopes to continue his progression at Leverkusen under the guidance of Schmidt.
"I made a giant leap in the current season under coach Roger Schmidt in my development," he said.
"Under his direction and in his system I have become a much better player.
"I've never enjoyed such trust as Roger Schmidt. I will do everything to repay him and Leverkusen."
Leverkusen currently sit in sixth place in the Bundesliga table after 21 matches, with only four points separating them and a place in the top three.
