The former Pontypridd, Bridgend, Celtic Crusaders and Harlequins outside back was released by the Scarlets in May of this year and will now join up with his new team-mates for pre-season training.
James will be reunited with former Lions colleague Dai Young, a fellow squad member when the Lions toured Australia and now head coach at the Blues.
"It's a great opportunity for me to join a team that is certainly on the up after their performances last season," said James, who was the first player to score 25 tries in Heineken Cup history.
"It's an exciting time to join the Blues as they move to the new stadium. They are probably the best supported team in Wales and had a huge amount of support last season in their Heineken Cup and EDF Energy Cup matches.
"The Blues have quality on and off the pitch and Wales is such a small place that I know a lot of the players from the Celtic Warriors days and playing for Wales, so I don't think there will be any problem settling in.
"It's an exiting time for me. I still have the desire to play for Wales and am totally motivated. I'm hungry to get back on the field and can't wait for the season to start."
James currently has 48 international caps to his name since making his senior Welsh debut 14 years ago, while fellow new signing Laulala has played twice for the All Blacks.
The 27-year-old Samoan-born Kiwi won caps against Wales in 2004 and Ireland in 2006 having been schooled at Wesley College - the same institution that helped Jonah Lomu on his way to international stardom.
A World Cup winner with New Zealand at Under-19 level, Laulala initially represented Counties Manukau and has since gone on to make more than a half century of appearances for both Canterbury and the Crusaders at NPC and Super 12/14 level.
"Dafydd, like Casey is a hugely experienced player and will be a valuable addition to our squad," explained three-times Lions tourist Young.
"He has proved with Scarlets, Wales and the Lions that he can consistently perform at the highest level and he will provide another significant option for our team.
"Both these signings help to strengthen our player base in a number of key areas in preparation for what is sure to be another intense period of highly competitive domestic and international rugby.
"With our commitment to the national side evidenced by the increased number of Cardiff Blues players in the Wales squad, quality players such as Casey and Dafydd will ensure our playing resources are not as stretched as they sometimes have been over recent seasons."