Dancing with the Stars host Tom Bergeron confirmed on last night's broadcast that Gilbert was injured when she hit her head on the ballroom floor in her performance of a paso doble with partner Maksim Chmerkovskiy.
"She injured herself and as a precaution she's gone to the hospital to get checked out," Bergeron told viewers.
Gilbert updated fans on her condition late Monday night following a check-up with her doctors.
"I'm alright. Mild concussion and whiplash. Very soon I will be safely home resting and being taken care of," the actress tweeted.
The Little House on the Prairie star also thanked Chmerkovskiy and fellow contestant Gavin DeGraw for rushing her to a waiting ambulance immediately after her injury.
"@MaksimC you are my champion. I adore you. @GavinDeGraw bless your heart for carrying me down those stairs," she wrote to both men.
Chmerkovskiy responded: "You're an ABSOLUTE ROCK STAR! You inspire me! Have so much more to say, but...... LOVE YOU!"
Gilbert and Chmerkovskiy had earned mixed reviews from the Dancing with the Stars judges, with Bruno Tonioli complaining that they "messed up the ending" and Carrie Ann Inaba referring to the pasa doble as the pair's "best performance by far".
The couple earned 22 out of 30 overall.
ABC has promised a further announcement on Gilbert's condition on tonight's Dancing with the Stars instalment, airing at 9/8c.
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Watch Melissa Gilbert and Maksim Chmerkovskiy's pasa doble below: