The club bid farewell to Andreazzoli following his fourth spell after Empoli, 19th in the standings, suffered their 13th league loss in 20 games when they were beaten 2-1 by fellow strugglers Hellas Verona on Saturday.
Andreazzoli had taken over from Paolo Zanetti in September after a 7-0 thrashing at Roma left them bottom of Serie A without a point after four games.
Nicola, whose previously coached Salernitana, saved them from relegation in the 2021-22 season.
"The coach has signed an annual contract with an option for a further season and will lead the first training session tomorrow afternoon," the club said in a statement.
The 50-year-old also managed Torino, Genoa and Udinese over the recent years.