The rugby player was enjoying a night out in Leeds, England on Wednesday (24Apr13) when he stepped out onto the road and was hit by a double-decker.
He was taken to a nearby hospital and remained under doctors' observation overnight.
Cipriani's manager James Williamson tells Britain's The Sun, "Danny's spending the night in hospital. X-rays and scans will be carried out overnight.
"He's obviously in pain. He was running across the road and just misjudged the speed of the bus."
Brook and Cipriani are rumoured to be a couple again following her split from rival rugby star Thom Evans in January (13).