The 19-year-old striker signed a new five-year contract with the Premier League champions on Tuesday before sealing his temporary switch to the Swans.
Abramah, who was also wanted by Newcastle, was a man in-demand after a hugely succesful loan spell in the Championship with Bristol City last season.
He scored 26 goals in 48 games for the Robins and has also been a standout performer for the England Under-21s.