Since joining Marco Silva's side, the 32-year-old shot-stopper has shown impressive form, earning himself a contract extension that will see him remain at Craven Cottage until the summer of 2027.
In the Premier League this season, only Arsenal's David Raya has outdone Leno's nine clean sheets, with Raya currently holding the top spot with 12 shutouts to date.
While Fulham have aspirations beyond mere survival, their victory at the London Stadium on Sunday confirms their safety from relegation.
Fulham to shell out £2m after securing top-flight status
Following the confirmation of their Premier League safety for another season, The Mirror reports that Fulham must now fulfil the multi-million payment to Arsenal as per the agreement for the former Gunners keeper.
The report adds that the initial fee was agreed at just £3m, but it has the potential to climb to £8m, and it is rapidly progressing towards that figure.
Leno made the short move to Craven Cottage from the Emirates Stadium in August 2022, with the agreement including performance-based add-ons such as a survival fee.
This term, the 32-year-old has featured in all 33 league matches for the Cottagers, who are currently 12th in the Premier League standings and still in the running to secure a second consecutive top-half finish.
The confirmation that Silva's side will compete in the top tier next season also marks yet another achievement for the Fulham boss, who himself signed a new long-term contract in December, extending his stay until the end of the 2025-26 season.
Leno was the Gunners' first-choice goalkeeper during his first three seasons with the club. However, he encountered a setback when he lost his position to Emiliano Martinez after being forced onto the sidelines with a knee injury he sustained against Brighton & Hove Albion in June 2020.
Although Martinez subsequently departed for Villa Park, Leno's return to the starting lineup was short-lived, with Mikel Arteta opting for new signing Aaron Ramsdale ahead of the 2022-23 season.
Despite the setback, Leno has recently enjoyed more time on the pitch than Ramsdale, who has since lost his place to new signing Raya. Meanwhile, the German has firmly established himself across London.
Following Andreas Pereira's brace against the Hammers, which secured Fulham's Premier League status this season, the Cottagers are now two points behind the 10th-placed Seagulls ahead of this weekend's clash against Liverpool at Craven Cottage.