(Federer will still be the No. 1 seed, because of the grass-court seeding formula used for the men).
The 20-time Grand Slam champion had already secured his return to number one in the world rankings with victory over Nick Kyrgios in the semi-final.
A single break of serve in the first set was enough for him to take that, though he did have to fend off two break points.
Federer delivered a short backhand past Kyrgios on his first match point to clinch the victory, which will move him back to No. 1 when the new world rankings are released Monday.
Kyrgios recovered his composure to push Federer again in the third and reach another tiebreak, where he took the first mini-break with a mad dash across court to send a forehand shot dipping over the net.
Nick Kyrgios put up a stirring fight.
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"We've played so many breakers and it could have gone either way".
Raonic won his last title at the 2016 Brisbane International.
The Canadian saved the lone break point he faced while breaking Pouille twice.
"It's a really positive step forward for me", Raonic said. "I'm happy to be back and healthy", Raonic tweeted after the match.
Raonic was ruthless with the serve and volley tactic that had proved so useful to him throughout the tournament to stay in touch with his Swiss adversary, but Federer remained composed to serve out the first set with 33 minutes on the clock.
Milos Raonic hasn't had the easiest season in 2018. However, Federer continued faultless and edged Raonic 7-3 in the tie-break. "The margins were very small, and there were very few chances and I'm glad in the tiebreakers I stepped up".
On Monday, Federer will begin a record-extending 310th week at the top of the rankings before seeking to defend his Halle grasscourt crown.