Lewis primarily played for Newport Gwent Dragons, London Welsh RFC, and Birmingham Moseley.
Robert came through the Newport Gwent Dragons Academy learning his trade with Ebbw Vale RFC and made his debut for the region in December 2007, coming off the bench away to Munster.
Following the unfortunate financial situation at London Welsh and its loss of a licence to continue to play in the RFU Greene King Championship, Rob returned to Ebbw Vale RFC in January 2017.
In his second season at Birmingham Moseley Lewis was announced as Captain, alongside Buster Lawrence and Sam Brown.
After a two season spell in Birmingham Lewis would go on to join Luctonians RFC, whilst also becoming Head Coach at Malvern College Independent School.