At the age of 17, lanky Dan Maloney played Junior B hockey with the Markham Waxers, where he was one of the team's best two-way players, and always showed an interest in the fisticuffs if need be. At 18, he moved on to major junior, suiting up for the London Knights in 1968-69. The following year Maloney received much more ice time and was gaining lots of attention from NHL scouts, who liked his ability to generate offense while at the same time showing a willingness to take care of the tough stuff, as evidenced by his 232 minutes in the penalty box.

The Chicago Blackhawks selected Maloney with the 14th pick overall in the 1970 NHL Amateur Draft. Maloney played in the Blackhawks organization for almost three years, and became known as one of the enforcers, both with Chicago and the club's minor-league affiliate in Dallas. Late in the 1972-73 season, he was traded to the Los Angeles Kings for Ralph Backstrom.

After spending two years on the west coast in relative anonymity, Maloney was traded to the Detroit Red Wings as part of a blockbuster deal that also saw Terry Harper move to the Motor City in the famous Marcel Dionne trade. Maloney spent the better part of three seasons in Detroit before being traded to the Toronto Maple Leafs at the 1978 NHL Entry Draft. He remained in a Maple Leafs' uniform until retiring in 1982 at the age of 31.

Following his career as a player, Maloney took to the coaching ranks, and served as the bench boss for the Toronto Maple Leafs from 1984 to 1986. He was not out of a job for long, as another former team he'd played with, the Winnipeg Jets, signed him to take over the head coaching duties on June 20, 1986, succeeding John Ferguson who had been filling in on an interim basis. Maloney lasted almost three years in the post, but sub-par on-ice performances and the inability to get past the powerful Edmonton Oilers in the playoffs led to his demise on February 7, 1989 when he was replaced by Rick Bowness.