The Sonics name comes from Bristol's links with the development of the Concorde supersonic passenger jet, which was built and tested close to the club's original ground of St Brendans Old Boys in Filton.

Bristol Sonics were granted membership of the Rugby League Conference in January 2003, taking their place in the South West Division alongside Gloucestershire Warriors, Somerset Vikings, Worcester Saints, Cardiff Demons and Oxford Cavaliers.

For the 2004 Rugby League Conference season, national expansion and restructure found Bristol Sonics placed in the new Western division of the RLC.

Brief relief came in the form of a second successive trip to the York International 9s in June, where the Sonics made the quarter-finals, securing a victory over French side Montpellier along the way.

Things started badly when the RFL announced on the eve of the season that one of the South West Division's new clubs, Thames Valley Cougars, would not be entering the league.

In a contest at Chase High School, Burntwood, Bristol triumphed 40–30 to become West Midlands Champions – the club's first significant silverware.

Bristol Sonics carried their fine 2007 form into the 2008 season, remaining unbeaten in the West Midlands Regional Conference with 11 wins and a draw.

Their remarkable run included a record 98–18 win over Redditch Ravens and a nailbiting 24-all draw with Coventry Bears 'A', as well as a dramatic, last-minute victory over long-time rivals Oxford Cavaliers on the final day of the league season.

After receiving a bye in the quarter-finals, Bristol faced East Division winners Hainault Bulldogs in the semi-finals at Gloucestershire Warriors' Chosen Hill Ground.

That match was played at Derby City RLFC's Haslams ground, and saw Bristol take on Moorends Thorne Moor Marauders from Doncaster.

The Sonics' success in winning the West Midlands Division and reaching the national Grand Final earned them a record number of nominations at the annual Rugby League Conference Awards.

On 18 October, Bristol Sonics were drawn at home in the preliminary round against British student champions Leeds Met Carnegie University.

After winning a play-off semi-final against Leicester Storm 16–8 at Aretians, they travelled to Old Coventrians to take on Minor Premiers Coventry Bears in the divisional Grand Final.

Bristol's captain Dom Swann saw a field goal attempt drift inches wide before Coventry's Luke Watts scored to give the bears a narrow 24–20 extra time win.

The Sonics led 16–8 at half time and eventually ran out 28–20 winners, with long serving captain Dom Swann being named man of the match.

They enjoyed a successful first season, coming second in the West of England Division of the Rugby League Conference behind old rivals Gloucestershire Warriors.