The dazzling multiverse adventure won seven awards including best picture, director and original screenplay.
Accepting her statuette, Yeoh said: "For all the little boys and girls who look like me watching tonight, this is a beacon of hope and possibilities.
"And ladies, don't let anybody tell you that you are ever past your prime."
Yeoh's co-stars Ke Huy Quan and Jamie Lee Curtis triumphed in the supporting actor and actress categories. In the history of the Oscars, no other film has ever won best picture, best director and three acting prizes.