The title was the 33-year-old Hingis's first since winning the doubles in Doha in 2007.
"Obviously it is very exciting, when you convert that match point, you are like, yes, we did it," said Hingis.
Since retiring in 2007, Hingis, a former world number one, has flirted with a doubles comeback.
Last year the winner of five singles and nine doubles grand slam career titles attempted a return with Daniela Hantuchova but found little success, winning just three of five matches and falling in the first round of the U.S. Open.
Hingis launched a second comeback this season, losing in the first round of Indian Wells, but looked right at home on the Miami hardcourts, returning to the winner's circle at an event she won twice (1998-99).
"Two weeks ago if you asked me, I probably would have had a completely different answer," said Hingis, when asked about her future plans. "Last week, I was like, I'm not sure if I want to put myself out there like this and lose first, second round.
"Now after this victory, things have definitely changed. I would be very happy to continue to play some more doubles of course."
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- Daniela Hantuchova