Swiatek will be the new world number one, while Osaka last topped the rankings in 2019Iga Swiatek maintained her dominant form in 2022 by beating Japan's Naomi Osaka in the Miami Open final.
And the 2020 French Open champion cruised to a 6-4 6-0 victory over Osaka to make it 17 consecutive wins.
The 20-year-old has also become the first female player to win the first three WTA 1000 events of the year.
She is just the fourth woman to win at both Indian Wells and Miami in the same season, after Steffi Graf (1994, 1996), Kim Clijsters (2005) and Victoria Azarenka (2016) - and is the youngest to win the 'sunshine double'.
Having won as a teenager at Rome last year, Swiatek has now won four of the last six WTA 1000 events overall.
Osaka was brought to tears by a heckler as she lost at Indian Wells last month, but in Miami she managed to reach her first WTA 1000 final since 2020, when she could not face Azarenka for the Cincinnati title because of a hamstring injury.
Osaka, whose family moved to Florida in 2006, told the crowd afterwards: "I know this isn't the outcome that you guys wanted but I'm having a lot of fun up here. Just to be in a final again means a lot to me."
She also thanked her team, saying: "They're the ones that keep pushing me forward after the things that happened two weeks ago, they're the rock that stays by my side."
The four-time Grand Slam winner, who is currently ranked 77, was unable to force a break point on Swiatek's serve.
The former world number one, 24, saved two break points in the opening game, but Swiatek later broke to go 3-2 up at the Hard Rock Stadium.
Osaka, playing in just her fourth event since taking a break last September, saved another break point in her next service game, only for Swiatek to close out the first set.
And Osaka was unable to hold her serve at all in the second set while claiming just five points on Swiatek's serve.
That ensured the Pole, who will top the world rankings as a result of Ashleigh Barty's retirement, has won her last six finals since losing her first tour final in 2019.
