Mancini was in charge of the Azzurris for five years and led them to glory at EURO 2020, beating England in the final.
The former Manchester City boss presided over a record 37-match unbeaten run between October 2018 and October 2021.
However under the 58-year-old's tenure, Italy failed to qualify for the 2022 FIFA World Cup in Qatar.
In all, Mancini was in charge for 39 wins, 13 draws and nine defeats with Italy.
A statement from the Italian Federation reads: "The Italian Football Federation announces that it has taken note of the resignation of Roberto Mancini from the position of coach of the Italian national team, received late yesterday evening.
"Thus concludes a significant page in the history of the Azzurri, which began in May 2018 and concluded with the 2023 Nations League Finals; in between, the victory at Euro 2020, a triumph conquered by a group in which all the individuals have known how to become a team.
"Taking into account the important and close commitments for the UEFA Euro 2024 qualifiers (10 and 12 September with North Macedonia and Ukraine), the FIGC will announce the name of the new national coach in the next few days."
Explaining his decision to step down on his Instagram account, Mancini said: “Resigning as CT of the Nazionale was a personal decision of mine.”
“I would like to thank Gabriele Gravina for the confidence he showed in me, as well as all members of the FIGC.
“I salute and thank all of my players as well as the fans, who have stood by me over the last five years. I will always hold the extraordinary victory at EURO 2020 close to my heart. It has been an honour.”
