On 31 August 2021, Léa Siliki joined EFL Championship club Middlesbrough on loan for the duration of the 2021–22 season.[5] Having not played a single minute since the manager who had brought Léa Siliki to Teesside, Neil Warnock, had been replaced by Chris Wilder, the midfielder was told by Wilder that he could leave the club during the January transfer window.[6] His return to action came in February 2022, being replaced at half-time during a 3–2 defeat to struggling Barnsley.[7]
On 22 July 2022, Léa Siliki signed for Primeira Liga club Estoril on a three-year contract.[8] On 1 September 2023, Estoril announced that Léa Siliki's contract had been terminated by mutual agreement, after he had been frozen out of the squad by manager Álvaro Pacheco.[9]
On 9 February 2024, Siliki signed with Gençlerbirliği in Turkey until the end of the 2023–24 season.[10]
In March 2022, Léa Siliki was subjected to racist abuse on Instagram after posting a celebration of Cameroon's qualification for the 2022 FIFA World Cup.[12]