Biggar featured in the Premiership in the white of Swansea RFC. He made his Ospreys debut as an 18-year old at the Millennium Stadium, coming off the bench late on in an EDF Energy Cup semi-final win over Saracens. On 12 September 2008, Biggar made his first Ospreys start in a Magners League game against Glasgow Warriors. Biggar kicked 9 points including a long range drop-goal as the Ospreys ran out 18-21 winners at Firhill.