Fognini eventually folded 6-1 in the final set in the blistering South London sun.
The 22-year-old world number two from Murcia, bidding to become the first player since Bjorn Borg to do the Roland-Garros-Wimbledon double in successive years, was often outplayed by the veteran Italian.
Fognini, the former world number nine, won the fourth set convincingly.
In his last game at Wimbledon, Fognini lost 7-5 6-7 7-5 2-6 6-1 to the five-time slam winner, favourite to take his third straight Wimbledon crown ahead of world number one Jannik Sinner.
Alcaraz beat Sinner in the longest French Open final earlier this month after the 23-year-old South Tyrolean had four match points in the fourth set.
ANSA
