Saudi Arabia face hosts Russia in the opening match of the tournament on June 14 while four-time champions Italy stay home following their failure to qualify for the first time in 60 years.
Made the scapegoat for Italy's first-round exit from the 2014 World Cup, Balotelli's four-year hiatus from the Azzurri squad ended when he was recalled by Mancini, appointed six months after Italy's shock failure to qualify for Russia following a playoff defeat to Sweden.
It took the 27-year-old Nice striker just 21 minutes to get on the scoreboard with his first goal for Italy since netting the winner against England at the 2014 World Cup.
Mancini appointed Italy manager
Italy have dropped to their lowest ever world ranking of 20th, but were in control against the 67th-ranked Saudis.
Mancini opted for a 4-3-3 formation with Gianluigi Donnarumma in goal and Sassuolo winger Matteo Politano handed his full debut.
Balotelli came out firing early with the Nice striker heading just wide off a Leonardo Bonucci cross.
He finally found a way through with a low drive under the outstretched arms of Saudi goalkeeper Mohammed Al Owais for his 14th goal in 34 appearances.
Napoli winger Lorenzo Insigne nearly added a second minutes later after picking up a pin perfect cross but defender Yasir Al Shahrani blocked.
An Alessio Romagnoli bicycle kick flew just wide with Domenico Criscito rattling the the crossbar.
Both Mancini and Saudi coach Juan Antonio Pizzi made substitutions in the second half with Balotelli making way for Andrea Belotti after 58 minutes.
"Without Italy, it just doesn't feel like a World Cup": Dino Zoff
And the 24-year-old Torino striker scored the second when he turned in a rebound ten minutes later.
Yahya Al-Shehri pulled Saudi Arabia back into the game four minutes later taking advantage of defensive error by Davide Zappacosta.
Leganes winger Al-Shehri picked up a Salem Al Dawsari flick and fired past the outrushing Donnarumma into an empty net.
The final ten minutes at the Kybunpark turned into a battle for the Italians with Donnarumma denying Fahad Al Muwallad an equaliser.
The Italians held on for their first win since their 1-0 World Cup qualifier away to Albania on October 9, which was followed by two draws and two defeats.
Italy play two more friendlies, against France on June 1 in Nice and the Netherlands on June 4 in Turin.
The Saudis play two more warm-up games, against Peru on June 3 and Germany on June 8 before kicking off their World Cup campaign.
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