During his time at Franklin’s Gardens, Manoa established himself as one of the most devastating players in the northern hemisphere.
Standing at 6ft 7ins and tipping the scales at 20 stone, Manoa brings a formidable physical presence to the pack and provides further competition for the number eight jersey.
Mulvihill said: “This is another significant signal of intent as we build towards the new season and a return to the European Champions Cup.
“Samu is a big, physical man, who will compete with Nick Williams for the number eight jersey and bring an abundance of experience to our pack.
“It is important that we take some of the work-load off Nick and Samu will work in tandem with him, ensuing that we have a real physical presence for the full 80-minutes.
Having spent three seasons at Toulon, he is looking forward to joining his new teammates and moving his family to the Welsh capital.
Manoa said: “I’m really looking forward to the next chapter and getting stuck in at Cardiff Blues.
“They had great season last year, winning the European Challenge Cup and sealing a return to the Champions Cup, so it is a great time to join.
“I have spoken to both John and Blaine at length, and have heard nothing but good things about the set-up at Cardiff Blues, the city itself and the region.
“My family is the most important thing to me and hearing about how well players and their families are taken care of at the Blues was a big lure. If they are happy, I am happy and can be at my best.