The 19-year-old French-born midfielder was spared jail after being found guilty of the attacks and was instead handed a fine and community service.
The district judge, Bodfan Jenkins, said in court that he was sparing Sainte-Luce prison: "Because your promising career could be compromised by prison time, I want to avoid taking such action."
Saint-Luce punched Anna Wadey, 22, unconscious and assaulted Laura Bennett, 23 at the Glam nightclub in Cardiff last November in what was described as an unprovoked attack.
Judge Jenkins ordered Sainte-Luce to pay £1,250 compensation to the two women and put him on a 10-week 8pm-6am curfew. He was also handed 180-hours community service.
However, after an internal inquiry, Cardiff City decided against letting Sainte-Luce continue his career at the Championship club.
"Cardiff City Football Club can today confirm that the contract for Kevin Sainte-Luce has been terminated with immediate effect," he said in a brief statement.
Sainte-Luce made just one appearance for the Cardiff first team after making his way up through the club's academy.