On 17 August 2018, Troost-Ekong joined Italian Serie A club Udinese. In his debut season in the Serie A, he made 35 league appearances and was booked four times, helping Udinese to 12th position. The next season, Udinese finished 13th, albeit with two more points. Despite the team's relatively lacklustre league campaigns, Troost-Ekong started (and played for the full 90 minutes) in memorable victories against AC Milan and Juventus in his two seasons at "Le Zebrette."