The 13th seed converted four of five break points to become the lowest seeded player to lift the trophy since fellow No. 13 seed Gustavo Kuerten's title run in 1999. Fognini will rise to a career-high No. 12 when the latest ATP Rankings are published on Monday.
This title in the Principality comes after a difficult start to the season. The nine-time tour-level titlist entered the Monte-Carlo Country Club with one win in his eight most recent tour-level encounters and had lost each of his four matches on clay this year.
The Italian, who on Saturday, became the first player to defeat Rafael Nadal en route to a clay-court title since Pablo Cuevas's triumph at the Rio Open in 2016, had also knocked out World No. 3 Alexander Zverev to reach the quarter-finals.
Fognini earns 1000 ATP Rankings points and receives 958,055 Euros in prize money. Lajovic gains 600 points and 484,950 Euros for his run to the championship match.
Fognini is the eighth player to win his first Masters 1000 title over the past 17 events at the elite level. In the 92 ATP Masters 1000 events prior to 2017 Rome, only eight players won their first Masters 1000 crown.