Giannini began playing for local side
Llanelli Wanderers RFC, and played for Llanelli Schools U15 and Scarlets U16. A captain for the Scarlets U18 side, Giannini made his first appearance for
Llanelli RFC in 2021. In 2022, Giannini was selected for Wales U18. Giannini made his debut for the Scarlets on 24 September 2022 against Ulster. Coming off the bench, Giannini became the second youngest player to represent the Scarlets. Giannini was selected for
Wales U20 in 2023, making his first appearance in a friendly against
Poland. He was subsequently named in the full squad for the
2023 Six Nations Under 20s Championship. On 3 February 2022, he made his first appearance, starting against Ireland. He made four appearances during the tournament. Giannini was named in the squad for the
2024 Six Nations Under 20s Championship, and appeared in one match, against
France. Giannini was released by the Scarlets at the end of the
2023–24 United Rugby Championship season. He subsequently joined
Swansea RFC ahead of the inaugural Super Rygbi Cymru season. == References ==