Coren Mitchell, 51, who is best known for hosting BBC quiz show Only Connect, welcomed June Violet Mitchell last week.
She gave birth to her first daughter Barbara, with David, 49, in 2015.
The news comes after Coren Mitchell posted a picture of herself in a red cloak at Halloween.
Writing on Xon Wednesday, Coren Mitchell said: "Many people are assuming my tweet yesterday was a Halloween costume.
She added: "Not at all; last week I had a baby and nothing currently fits me except cloaks. Luckily, Only Connect is a pre-record. Happy All Saints Day!"
The birth was also shared in The Times on Wednesday, with a statement that reads: "On 26th October 2023 to Victoria and David, a daughter, June Violet sister to Barbara."
Coren Mitchell, who is also a professional poker player, married David Mitchell in 2012, two years after confirming their relationship.
Mitchell is best known for playing Mark in comedy sitcom Peep Show and for his work with co-collaborator Robert Webb.
The pair met at Jonathan Ross's Halloween party in 2007, with Mitchell saying in his autobiography Back Story that he was "hopelessly in love" despite Coren Mitchell being in a relationship with someone else at the time.
"I told no one about it. I didn't tell my closest friends or my parents of the enormous sadness that overshadowed my life," he wrote.
Coren Mitchell has kept her pregnancy concealed from viewers and fans on social media,but hinted two weeks agoby saying she was "taking a little sabbatical" from her TV column for The Telegraph.
She also hosted an episode of Have I Got News For You on BBC One on 6 October.
The TV presenter Victoria Coren Mitchell has announced the birth of her second child with comedian David Mitchell.