Antonini started his career as part of the youth system of Grêmio before moving to Italy to join amateur club Meda.[1] He was subsequently scouted by Inter Milan who signed him for their youth teams.[1] After a few appearances with friendly games for Inter, Antonini left the Nerazzurri for Cagliari, joining the Under-19 Primavera team;[2] he shortly thereafter made his professional first team debut in a 2016–17 Coppa Italia game against Sampdoria ended in a 0–3 away loss, on what turned to be his only senior appearance with the Sardinian club.[3] Despite having served as team captain for the Under-19 team of Cagliari, he was released in July 2018 and then left to move back to Brazil, re-joining Grêmio.[4]
Serie C
Arezzo
In February 2020, Antonini returned to Italy, joining Serie C club Arezzo.[5]
Serie D
NibionnOggiono
After failing to make any appearances for Arezzo, he left the Tuscan club to join Serie D club NibionnOggiono, with whom he finally managed to play as a regular.
Ravenna
His impressive performances won him the interest of the ambitious Serie D club Ravenna, who signed him in July 2021.[6]
Return to Serie C
Taranto
In July 2022, Antonini signed for Serie C club Taranto.[7] He quickly affirmed himself as a staple for the Apulians, playing as a regular and being praised for his performances, which gained him a contract extension until 30 June 2025.[8] In the 2023–24 Serie C season, Antonini established himself as one of the best defenders in the league, as well as a prolific goalscorer (with four goals in his first sixteen games),[9] and then being linked to higher division clubs and praised by his manager Ezio Capuano as player with Serie A potential.[10]
Antonini, therefore, experienced the best seasons of his career in Taranto, revealing himself to be a key player for the rossoblù.
Serie B
Catanzaro
On 21 January 2024, Antonini joined Serie B side Catanzaro for an undisclosed fee, signing a contract until June 2027.[11][12]