Released from jail in the afternoon, Willis spoke briefly to reporters as he was making his way to a car driven by his criminal defense attorney, Walter Reynoso.
Asked what he had to say to his fans, the left-handed pitcher said: "I'll be all right, I'll be all right. ... I'll do a better job."
According to police reports, Willis drove up to a South Beach nightclub, got out of his black Bentley and urinated on the street. He got back into his car and was arrested on Washington Avenue close to the Mansion nightclub.
Willis spent the rest of the night in jail, and bond was set at $1,000.
Marlins senior vice president of communications and broadcasting P.J. Loyello said the organization had no comment on Friday morning.
A call to Willis' agent, California-based Matt Sosnick, was not immediately returned.
Raised in Alameda, Calif., Willis makes South Florida his home year-round.
According to police, Willis was confused and disoriented; he had blood-shot eyes and slurred speech.
"[The officer] conducted a field sobriety test on the scene," Miami Beach police spokesman Bobby Hernandez told reporters late Friday afternoon. "Mr. Willis failed those tests. He was brought here to the police station, where he was offered the Breathalyzer. Unfortunately, he refused the Breathalyzer, and he was subsequently arrested."
The high-profile Willis is one of the rising stars in the league, and the left-hander is immensely popular.
The National League Rookie of the Year in 2003, Willis has already been to two All-Star games, he's been a 20-game winner and he represented the United States in the 2006 World Baseball Classic. He was the organization's Roberto Clemente Award nominee, an honor that recognizes his achievements on and off the field.
With a 58-39 career record, Willis is the Marlins' all-time leader in victories. In 2005, the lefty went 22-10 with a 2.63 ERA, pacing the Major Leagues in victories. He was 12-12 with a 3.87 ERA in 2006.
Willis is very active in the community, visiting numerous schools and representing the organization at holiday-related events.
Willis made $4.35 million in 2006 and is in line to make more than $6 million in arbitration this season.
Willis' mother, Joyce Harris, who lives in Alameda, learned of her son's arrest while watching television.
In an interview with the South Florida Sun-Sentinel, she said: "I felt like in my heart I owed it to the people in Florida, because I just feel like after all the friends I've made, how all the people have treated us, I wanted to say something on behalf of the whole family. In my heart, I'm really sorry and really sad, and I'm still in shock. ... Dontrelle just made a mistake. I don't know what else to say. Whatever Dontrelle needs to do, I'm sure he will get it done.
"I hope everybody can kind of forgive us. I'm taking responsibility, too, for what has happened. It'll take a little bit for people to process. That's human nature, but he's still the same loving kid who loves the game and is going to give Florida all he has when he's on the field."
Marlins manager Fredi Gonzalez told the Palm Beach Post: "It's sad. I hate to see anybody go through that, especially a guy like him who has done so much for the community. But I really don't have a comment, because I haven't talked to anybody with the team. All I know is what I have read on the computer."