He was selected by the Cleveland Browns in the fourth round of the 1984 NFL draft.

[2] He was a teammate of quarterback Doug Flutie at Boston College, earning Second Team All-American honors.

Brennan played in nine NFL seasons from 1984 to 1992 for the Browns, Cincinnati Bengals, and San Diego Chargers.

Late in the fourth quarter, Brennan hauled in a go-ahead touchdown pass from Bernie Kosar along the left sideline to give the Browns a 20–13 lead over the Broncos.

This biographical article relating to an American football wide receiver born in the 1960s is a stub.