Serena Williams of the United States plays a forehand against Carla Suarez Navarro of Spain in the final during the Miami Open on April 4, 2015 in Key Biscayne, FloridaSerena Williams of the United States plays a forehand against Carla Suarez Navarro of Spain in the final during the Miami Open on April 4, 2015 in Key Biscayne, Florida (AFP Photo/Clive Brunskill)
The 33-year-old US superstar, who won her 19th Grand Slam title in Australia this year, lifted the trophy in the elite premier level tournament for the third straight year.
She also won three straight Miami titles from 2002-04 and back-to-back titles in 2007-08.
Williams had already surpassed Steffi Graf for most Miami triumphs with her win last year.
On Saturday she joined Graf, Martina Navratilova and Chris Evert as the only Open Era players to win the same event at least eight times.
Graf won nine titles in Berlin, Evert won eight in Hilton Head, and Navratilova achieved the feat in seven tournaments -- including her nine Wimbledon titles.
"It feels really good to have eight under my belt," Williams said.
"Can't say I thought I would win eight, especially in the beginning of the week," added the champion, who had struggled with her serve and unforced errors in previous matches.
"I had a couple matches where I had nearly 60 unforced errors in both, so I just needed to kind of get my mind back there and say, 'Serena, you normally don't play like this, so just go to how you normally play," she said of how she tried to regroup after clawing past world number three Simona Halep in the semi-finals.
In Suarez Navarro, Williams faced an opponent she had beaten in four prior encounters without dropping a set.
- Serena's the best -
World number 12 Suarez Navarro, playing in the biggest final of her career, wasn't surprised to find the winners zinging past her from every part of the court.
"When I play with Serena I know that she's the best," Suarez Navarro said. "She has the game to make me play bad.
"But this time I believed in me, in how I'm playing the other matches. I tried. I tried until the last point, but it was tough and difficult for me."
Suarez Navarro held her nerve and her serve through the first five games.
But Williams converted her third break chance of the sixth game to grab a 4-2 lead in the opening set, consolidating the break with an easy hold.
Suarez Navarro saved two set points against her serve in the next game, but Williams gave herself another chance with a forehand winner and Suarez Navarro handed her the set with an error.
Suarez Navarro had a chance to break in the first game of the second set, but Williams held on then broke at love in the next game.
She polished off the triumph in just 56 minutes.
It was a satisfying win for Williams, coming after a troublesome knee prompted her to forfeit her scheduled semi-final at the premier level tournament in Indian Wells a fortnight earlier.
Williams hasn't lost a competitive match since October, when she fell to Halep in the round robin phase of the WTA Finals -- which Williams went on to win.
Suarez Navarro lost her seventh WTA final in eight appearances. But her fine week in Florida, where her victims included Venus Williams, will see her break into the top 10 in the world rankings on Monday.