Medvedev saved two breaks points while serving for the match at 5-4 in the second set before winning the next four, three of them with aces to close out his dogged Belgian opponent.
It was the second title of the year for Medvedev, who had lost on the past two Sundays, to Nick Kyrgios in Washington and Rafa Nadal in Montreal.
The pressure perhaps showed in the final game when Medvedev hurled his racquet to the ground after losing a point, but the temper tantrum was short lived and he regrouped quickly to clinch his fifth title in two years.
Earlier, Goffin did well to force a first set tiebreak by holding serve, including winning a 29-rally point.
But the Belgian, without a victory since 2017, lost the tiebreak on a double-fault.
Medvedev, who beat world number one Novak Djokovic in the semi-finals, plans a short rest before the US Open starts in eight days.
On the women’s side, American Madison Keys overcame late leads by Svetlana Kuznetsova in both sets to defeat the Russian for the Cincinnati Masters title on Sunday.
The confidence-boosting 7-5 7-6(5) victory sent Keys into the US Open later this month as the world's number 10 ranked player.
