The 24-year-old Italian fired 15 aces in beating Germany's Zverev 6-3, 7-6(4) after an hour and 53 minutes - boosting his streak of consecutive sets won at the elite Masters 1000 level to 32.
Sinner is trying to become the first man since Roger Federer in 2017 to complete the "Sunshine Double" by winning titles at Indian Wells and Miami in the same year.
"Standing here again in a final means very much to me," Sinner said. "We'll try to push in a couple of days but in any case it has been an incredible swing."
Reigning Wimbledon champion Sinner, a four-time Grand Slam winner, also beat Zverev two weeks ago in the Indian Wells semi-finals and seeks his second Miami crown in three years.
"Coming here, trying to produce some good tennis, that was my main goal," Sinner said. "Trying to play as many matches as possible. I couldn't do better. I'm very happy."
Also attempting a "Sunshine Double" is world number one Aryna Sabalenka of Belarus, who defends her Miami crown against American fourth seed Coco Gauff in Saturday's WTA final.
Lehecka's win over Fils
Lehecka, 24, dominated France's Arthur Fils 6-2, 6-2 on Friday to reach the men's final at the ATP and WTA Miami Open.
Fils, the 28th seed, had not dropped his serve in the tournament but was broken four times by 21st-seeded Lehecka, who advanced after 75 minutes at Hard Rock Stadium, home of the NFL's Miami Dolphins.
"He's an incredible player," said Sinner. "He's going to be for sure more free than me, but I try to control whatever I can control, and the rest we'll see how it goes."
Sinner is trying to become the first man to complete the "Sunshine Double" by winning titles at Indian Wells and Miami since Roger Federer in 2017.
Also attempting to complete the "Sunshine Double" is world number one Aryna Sabalenka of Belarus, who plays in Saturday's WTA final against fourth-seeded American Coco Gauff.
Lehecka didn't face a break point and broke Fils for the first time in the tournament in the opening game of the match when the Frenchman netted a forehand.
He broke Fils early in the second set and again on a backhand cross-court service return winner for a 5-2 lead, then held serve for the triumph, leveling his career mark against Fils at 2-2.
Lehecka seeks his third ATP title after Adelaide in 2024 and Brisbane in 2025. It's the eighth career final for the Czech but his first at the elite Masters 1000 level.
Fils injured his back at last year's French Open and returned only last month, when he was a runner-up at Doha and beat Lehecka in a quarter-final.
It was the first Masters 1000-level semi-final for Fils and just the second for Lehecka after 2024 at Madrid, when he retired due to a back injury that sidelined him for more than three months.
Lehecka is winless in three matches against Sinner without taking a set and 1-1 against Zverev.
Sinner hopes to reach the final and continue his streak of 30 consecutive sets won at the Masters 1000 level.
Sinner leads the career rivalry with Zverev 7-4 and owns a six-match win streak over Zverev, who last beat the Italian in 2023. Sinner's run includes a victory over the German two weeks ago in the Indian Wells semifinals.