[8] Bettinelli joined Conference Premier club Dartford on 17 August 2012 on a one-month loan to gain first-team experience.

[22] He made his debut for the club on 26 August in the second round of the League Cup away to West London rivals Brentford, keeping a clean sheet in a 1–0 victory.

[24] On 5 December, he was sent off after 18 minutes in a 5–0 loss to Watford at Craven Cottage for fouling Matěj Vydra, conceding a penalty that Troy Deeney put past substitute goalkeeper Gábor Király.

[25] Bettinelli signed another contract extension on 30 August 2017, keeping him at Fulham until June 2020 with an option in the club's favour to extend for a further year.

[27] Fulham finished third and qualified for the play-offs, defeating Derby County 2–1 on aggregate in the semi-final and Aston Villa 1–0 in the final at Wembley Stadium.

[30] For 2018–19, he lost his place to on-loan Spaniard Sergio Rico shortly before Jokanović's dismissal in November, and the situation remained the same under new manager Claudio Ranieri.

[35] He made his Chelsea debut on 8 January 2022, in the 5–1 FA Cup third round victory over National League side Chesterfield at Stamford Bridge.