The Bulls began play in the 1998 season as a charter member of the competition now known as the AMNRL. Originally known as the Glen Mills Bulls, the team was affiliated with the Glen Mills Schools in the Glen Mills area of the Delaware Valley from 1998–2006. For the 2007 season they relocated to nearby Aston Township and adopted their current name. Since their inception the Bulls have been the AMNRL's most successful team on the field, winning a total of six league championships, more than any other team. Additionally they have competed in the league playoffs every year of play, advancing to the Grand Final every year from 1998–2008.
The team was founded in 1998 by Australian retired rugby league player David Niu. Niu had been involved in promoting rugby league in the United States since the early 1990s, and introduced the sport to the Glen Mills Schools in the Glen Mills area of Delaware County, Pennsylvania, where he was employed as a teacher. In 1998 Niu's former teammate, Matthew Elliott, coach of England's Bradford Bulls team, visited Philadelphia and saw Niu's plans for the sport. Elliott and the Bulls agreed to support the Glen Mills club in its first year, providing them jerseys and the Bulls name. For the first nine years of operation the Bulls team and staff were made up of employees of the Glen Mills Schools, and the team played its games at the school's Jack Pearson Stadium in Concordville.
After the 2006 season the Bulls ended their affiliation with the Glen Mills Schools and relocated to nearby Aston Township, renaming themselves the Aston Bulls. Since the relocation they have continued their uninterrupted streak of playoff appearances, advancing to the Grand Final in 2007 and 2008.
In their inaugural season the Bulls wore jerseys donated by the Bradford Bulls. Thereafter they adopted the colors of blue and white with the uniforms being predominantly blue, similar in style to the National Rugby League team the Canterbury Bulldogs, after the two clubs agreed to an affiliate partnership with each other. After the name change to the Aston Bulls, the club adopted the new colors of gold and white for their home uniform.