Kirsty Gallacher, 41, was stopped by police at 11:30am yesterday as she drove to pick up her children.
The TV presenter was seen driving erratically.
Kirsty has two sons with her former husband, Paul Sampson, of ex-England rugby union fame.
A source said: “Kirsty had enjoyed a night out and was driving to pick up the children from Paul’s house.
“As of 5pm last night, she was still in custody.”
Some hours before her arrest in the Eton area, Kirsty posted a snap of herself enjoying a night out with friends at the Winning Post pub in nearby Winkfield.
While she did not have a drink in her hand at the time, pal Annie Hoy could be seen in the picture holding a glass of champagne.
Earlier, Kirsty had appeared on Sky Sports News alongside Jim White for a 6pm show to look ahead to the start of the new Premier League season.
According to The Sun, her family are said to be furious following her arrest.
Kirsty, who briefly dated rubgy star Danny Cipriani before she struck up a romance with a mystery man earlier this year, is considered to be one of the faces of Sky Sports News.
She will celebrate her 20th anniversary with the channel next year.