The Isle of Axholme star received standing ovations over the weekend as she returned to her leading role in Funny Girl at the Savoy Theatre.
Her part had been taken over by understudy Natasha J Barnes after she stepped down from the show in May following concerns about her health.
Daily Telegraph theatre critic Dominic Cavendish wrote: "If she's still tired and frayed, she showed not a jot of fatigue for two hours on Saturday night."
He added that her return had been "greeted by protracted applause from the audience at the start and a standing ovation at the end - a tsunami of affection which she gamely took in her stride, beaming, and jabbing a thumbs-up in thanks".
Sheridan and Natasha will take it in turns to play the role of Fanny Brice before the show ends on October 8.
When Smith took time off from the role in May the producers said she would get "the rest and support she needs".