Nicola was sacked by Livorno in January, with Di Carlo appointed with the club lying 19th in Serie A at the time.
However, results failed to improve under Di Carlo, with a 3-0 defeat at Milan on Saturday meaning Livorno remain second-bottom having taken just one point from their last six top-flight outings.
Livorno have subsequently decided to cut ties with the 50-year-old, and have entrusted Nicola - who oversaw their promotion from the second tier last term - with the unenviable task of trying to ensure Livorno's stay in Serie A is longer than one season.
"AS Livorno officially announce that Domenico Di Carlo has been dismissed as the first-team coach," read a statement on the club's official website.
"Livorno thanks Mr Di Carlo for his dedication and professionalism.
"The post of coach Livorno's first team has been entrusted to Davide Nicola."
Livorno are three points adrift of safety with just four matches remaining.
