He is the brother of fellow New South Wales and Australian representative, and Newtown player Viv Farnsworth.

In NSWRFL season 1910, he joined the rugby league ranks and commenced playing with the Newtown club.

[4] Farnsworth returned to the Newtown club as coach for part of the 1924 NSWRFL season.

[7] Bill Farnsworth was the great-uncle of the Parramatta Eels ex player and CEO Denis Fitzgerald.

In 2008, the centenary year of rugby league in Australia, Farnsworth was named as five-eighth of the Newtown Jets 18-man team of the century.