Sardella went through the youth system at KVK Wemmel and FC Brussels before moving to RSC Anderlecht.
In the summer of 2019, Mauves coach Vincent Kompany transferred him to the Anderlecht first team, with Sardella making his debut in the Brussels side's third league game of the 2019-20 season in a 0-0 draw against KV Mechelen as a starter.
In his second season, he started eight games in a row from mid-December to late January, at the expense of more experienced players such as Bohdan Mykhaylychenko and Michael Murillo.
On 30 March 2024, Sardella scored for the first time in his career in the top flight for the only goal in a 1-0 win over defending champions Royal Antwerp in the title play-offs.
Sardella made his debut for the Belgium senior team on 17 November 2024, as he was subbed on in the 93rd minute in a UEFA Nations League group stage match against Israel, which ended 1-0 in favour of the latter.