The 25-year-old Morocco international has made four appearances in the Barclays Premier League, all as a substitute, for the Reds since joining them from Dutch side Heerenveen a year ago.
Hughes told stokecityfc.com: "Oussama had a few options and I'm delighted he has chosen to join us.
"He's an exciting player, who has great pace and is very direct and will certainly add another dimension to what we already have at the club."
Stoke chief executive Tony Scholes said: "Mark identified the need to add more pace to the team and Oussama certainly fits the bill in that regard.
"He is an exciting talent and will certainly strengthen the resources at Mark's disposal this season."
For the big stories and the banter follow us on Twitter: @tribalfootball