An American consortium led by Stephen Kaplan and Jason Levien took over in July, inheriting Guidolin as manager.
But after a six-match winless run, the Italian has been replaced by former United States boss Bradley.
"We can confirm the club has parted company with Francesco Guidolin, who will be replaced by Bob Bradley," Swansea wrote on Twitter.
Former Udinese boss Guidolin joined Swansea in January as head coach and was given a two-year contract in May.
Ryan Giggs and Gianfranco Zola were among those to have been linked with the Swansea job
L ast week there were reports club chairman Huw Jenkins had met with Bradley at Bristol Airport
Bradley has been working at French club Le Havre in Ligue 2.
Swansea's only wins this season were at Burnley on the opening day of the Premier League season and against Peterborough in the EFL Cup.
Swansea lost in the next round to Manchester City, while the only Premier League point in five games was a 2-2 draw with Chelsea.
Manchester City and Liverpool have beaten the Swans in successive weeks and they travel to Arsenal on October 15, following the international break.
Source : PA
Source: PA