Ganna won gold ahead of compatriot Jonathan Milan (22), to add to the titles he won in 2016 and from 2018 to 2020, after finishing third last year in Roubaix.
The 2020 and 2021 road time-trial world champion crowned his triumph by setting a new world record of 3min 59.636sec at the Saint Quentin en Yvelines velodrome outside Paris.
The Olympic team pursuit champion had arrived at these worlds on the back of another world mark, breaking the mythical one-hour record, with 56.792km at the Grenchen track in Switzerland last Saturday.
The 26-year-old had bettered the surprise record set by Britain's Daniel Bigham (31), a performance engineer at Ganna's Ineos Grenadiers team on the same track last August, which he had attempted in order to collect data for the Italian's quest.
Bigham finished fourth in the pursuit on Friday, beaten by Portuguese Ivo Oliveira (26) in the match for bronze.
The Netherlands took two gold medals with veteran rider Yoeri Havik (31) winning the points race and compatriot Jeffrey Hoogland (29) successfully defending his 1km time-trial title.
Havik (31) finished ahead of Germany's Roger Kluge (36) and Belgian Fabio van den Bossche (22) over the 160 laps covering 40km, interspersed with 16 sprints.
Hoogland (29) dominated France's Melvin Landereau (25) in the final in an event he won in 2018 and 2021 with Spaniard Alejandro Martinez (25) taking bronze.
