Berahino joined the club from West Bromwich Albion in January 2017, was involved in a number of disciplinary issues last season.
The issues that he was involved with led the then manager Paul Lambert removing the striker from the first-team.
Berahino told SkySports: "I have made some mistakes. I have let myself and the people around me down."
"But it's part of life and you have got to try and better yourself every day and try to improve as a player."
"I want to try and do the best I can to help the team, obviously, and put Stoke back where they belong."
The 24-year-old will want to get back into goal scoring form, after a poor tally last season.
The last time Berahino scored a goal was in a 3-2 victory over Crystal Palace in February 2016.