The 54-year-old Welsh MP had been “laid low” by the virus since the end of December, according a statement on her Twitter account.
Her team tweeted on Saturday evening: “Jo has asked us to let you know that she is being treated in hospital for Covid. Thanks for all your good wishes we will give an update when we can.”
Labour leader Keir Starmer was among those wishing Ms Stevens well. He tweeted: “Get well soon Jo, a dear friend and colleague.”
Welsh first minister Mark Drakeford said: “All of our thoughts and best wishes are with Jo for a speedy recovery.
“Thank you to Jo’s constituency team for continuing to support Cardiff Central constituents at this difficult time.”
Ms Stevens’ team had first revealed that she was ill with coronavirus on New Year’s Eve.
They tweeted: “Jo has been laid low with COVID for a while so on behalf of us and Jo, Happy New Year to everyone across #CardiffCentral.
“Here’s to a healthier and better 2021. Tonight we’ll be thinking of all those who have lost loved ones to this awful virus.”
Ms Stevens was elected as MP for Cardiff Central in 2015 and served as shadow solicitor general and shadow Welsh secretary under Jeremy Corbyn. She quit the shadow cabinet in 2017 in order to vote against Article 50.
Kier Starmer appointed her as shadow secretary of state for digital, culture, media and sport in April 2020.
