With about 90 percent of the precincts reporting as of late Tuesday, Duggan led with 68 percent of the vote to 27 percent obtained by State Sen. Coleman Young II.
"Thank you, Detroit," Duggan told a packed crowd at a hotel. "I saw the numbers come in and it was just overwhelming."
Young, 34, raised $22,000 to Duggan's $1.6 million for the campaign. Campaign manager Adolph Mongo said Young's name, the same as the city's first black mayor, was worth $2 million.
Coleman A. Young was elected in 1973 as Detroit's first black mayor. He decided not to seek re-election in 1993 and died in 1997 after a long illness.
Young kept out of the limelight in the days leading to the election, relying on his father's reputation and press events.
Duggan, 59, kept up a busy schedule of public events in the past few months. He also attended community meetings and knocked on doors.
Duggan also was endorsed by prominent labor groups, including AFSCME and AFL-CIO, clergy and 24 former cabinet members and appointees of Young's father, who was Detroit's longest-serving mayor.
"We ran an old-fashioned campaign. No TV, no radio," he said. "We won it in the streets."
Duggan was elected in 2013, the city's first white mayor since 1973. He won the primary that year as a write-in candidate. Detroit is more than 80 percent black.
The next highest vote getter on Tuesday's ballot was first-time candidate Donna Marie Pitts at nearly 1 percent. Court records in Wayne and Oakland counties show Pitts has multiple felony convictions dating to 1977 for offenses including firearm charges and assault. Five other candidates and write-ins received the remaining votes cast.