Friel was first elected as mayor of Brantford in the 1994 municipal election, defeating one-term incumbent Bob Taylor. He was only twenty-seven years old at the time. He was re-elected in 1997, defeating right-wing candidate Andy Woodburn by a significant margin. He initially planned to stand down in 2000, but later changed his mind and was re-elected for a third term. Friel became mayor during a period of economic difficulties for Brantford; shortly after his election, he described the city as having the worst downtown in Canada. He later presided over a period of economic growth for the city. Friel initially opposed the Brantford Charity Casino, describing it as a "scam" designed to shift money from the city to the province. He was quoted as saying, "What bothers me is that the government used to do these capital projects to build a country.... Now the government is doing work that is building gaming. It's like they've given up, there's no creativity." He later accepted the casino's presence and tried to ensure it would provide some benefits to his community, though he still described it as an economic mistake. He helped establish Laurier Brantford, a local division of Wilfrid Laurier University. He was also mayor when the Brantford Eaton's closed and took part in overseeing the site's transformation into a call centre. During his second term, he spoke in favour of keeping the Brantford Hydro-Electric Commission as a public utility. Friel encouraged merger discussions between Brantford and neighbouring Brant County in 2000. At one stage, he said that he would ask the province to impose a decision on restructuring if the county declined talks. BrantCounty MayorRon Eddy strongly opposed this position, and Friel later acknowledged that producing a local agreement would be impossible. During the same period, Friel argued that the Six Nations people have a legitimate claim to the land surrounding the Grand River, six miles in each direction. Generally, Friel was known for having good relations with local indigenous groups. Friel strongly supported Brantford's anti-smoking by-law, citing his own father's death from lung cancer at a relatively young age. He himself took a three-month leave of absence in 2002 due to serious health issues. Friel was defeated in the 2003 mayoral election, losing to Mike Hancock by only fifteen votes. He chose not to seek a recount. He challenged Hancock again in the 2006 election and lost by 165 votes. When Hancock did not seek re-election in 2010, Friel ran for mayor again and won by a significant margin. A newspaper article from 2000 described his political style as "flamboyant, sometimes truculent." When running for re-election in 2003, he acknowledged that he had been an unorthodox mayor.
