Dolan, 25, has made 10 appearances for the Eagles, including an eye-catching man of the match performance against NZ Maori, has this week been named in a 50-man USA training squad for the Rugby World Cup, alongside fellow new signing Blaine Scully.
The Florida-born ace - who stands 6ft 6in and weighs 18st 2lb - joined Northampton Saints in December 2013 and made his senior debut for the English Premiership club against Leicester Tigers in the LV=Cup in January.
Billy Millard, General Manager at Cardiff Blues who has previously worked with Dolan at USA Rugby, said: "Cam is a very athletic and skilful player who can play lock and at 6 and 8 in the back row.
"His aerial skills are outstanding, he looks for work and he has had exposure to the strong culture at Northampton Saints.
"Cam will add real energy to our group and is hungry to build on an outstanding USA international career."
Educated at Life University, where he was a four-time All-American and a National Champion, Dolan is a former captain of the USA Under-20s at the 2009 IRB Junior World Trophy.
Dolan made his first start for the senior USA team in the 2013 IRB Pacific Nations Cup match against Fiji and later that year was named captain for the USA Select XV in the Americas Rugby Championship.
Factfile:
Full name: Cameron Alexander Dolan
Born: March 7, 1990, Florida, USA
Major teams: Northampton Saints, United States of America
Position: Lock/Back Row
Height 6ft 6in
Weight 238lbs
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