The 25-year-old from Sydney captured his eighth career ATP title after dropping four straight finals since downing American Tommy Paul in last year's final, the most recent coming last month at Rotterdam.
World number nine de Minaur, a two-time winner also at Atlanta, dispatched 11th-ranked Ruud after one hour and 57 minutes, improving to 2-0 against his European foe after winning their only prior meeting at the 2019 ATP NextGen Finals.
Ruud, a two-time French Open runner-up and the 2022 US Open runner-up, missed out on his 11th ATP title for the second week in a row after dropping last week's final at Los Cabos to another Aussie, Jordan Thompson.
Ruud's most recent ATP crown came last April at Estoril.
The players exchanged praise after the match, Ruud telling de Minaur: "Fantastic playing all week. Too good today. Seems like you are enjoying Acapulco quite well. You did a great job."
De Minaur replied: "Great stuff. It was hard work. Thank you for a great match."
