The 37-year-old, who set the record for most Halle titles more than a decade ago, earned his 10th title after defeating David Goffin of Belgium 7-6(2), 6-1 in one hour and 23 minutes, reported Efe news.
Federer has extended his record to 102 titles throughout his career, only seven away from equaling Jimmy Connors' record.
After eliminating John Millman, Jo-Wilfried Tsonga, Roberto Bautista, and Pierre-Hughes Herbert, Federer finished the tournament victorious without losing one service during the final match, saving three break points in the course of play.
Goffin squandered those three points in the fifth game of the first set, and although he managed to get Federer to a tiebreaker, he lost his service twice.
Goffin's defeat counted as number eight out of nine career encounters with Federer, and the second in the same tournament.
Federer eliminated the Belgian back in 2016 in the quarterfinal round 6-1, 7-6 (10).
This is the third title, following Dubai and Miami, for Federer, who seemed to be rounding into form ahead of the tennis grass-court Grand Slam at Wimbledon, a tournament he has won a record eight times in his illustrious career.
Federer, who is considered the greatest male tennis player of the game, was eliminated from Wimbledon last year in the quarterfinals by Kevin Anderson of South Africa.
He is set to occupy third place in the ATP rankings to be released Monday.
( With inputs from IANS )