Dineen signed with the expansion Ottawa Senators on August 31, 1992. The Senators assigned Dineen to the San Diego Gulls of the IHL to begin the 1992–93 season. With the Gulls, Dineen had six goals and 29 points in 41 games, earning a promotion to the Senators. Dineen played in his first game with Ottawa on January 21, 1993, where he was held without a point in a 7–2 loss to the Minnesota North Stars. On February 8, Dineen earned his first two points with the Senators, both assists, in a 4–2 win over the Buffalo Sabres. On February 25, Dineen scored his first goal with the Senators against Tom Barrasso of the Pittsburgh Penguins and added an assist in a 2–1 win. In 32 games with Ottawa, Dineen had two goals and six points.