Lewis, 42, will be the Giants' defensive coordinator, the same position he held the past four seasons with the Steelers. He interviewed Thursday for five hours with Coughlin and Giants officials, was said to have been very impressive, and was offered a contract. He returned home to Pittsburgh on Thursday night to discuss the opportunity with his wife, and accepted the deal Friday afternoon.
The New York Jets had also been interested in hiring Lewis to fill their coordinator spot, a vacancy that was created when coach Herm Edwards fired Ted Cottrell.
Details of the Lewis contract were not immediately available.
There is little doubt, though, that Coughlin coveted Lewis as his initial hire. As he was riding to the press conference at which he was announced as the Giants' new head coach, Coughlin noticed a newspaper story reporting that Lewis had been fired in Pittsburgh. He told a companion he had to get in touch with Lewis quickly, because he knew Lewis would be a hot commodity on the open market.
In four seasons as the Steelers coordinator, Lewis never had a unit rank lower than ninth statistically in overall defense, and that was this past season. Pittsburgh was seventh two times under Lewis, in 2000 and 2002, and rated No. 1 in 2001.
"Tim Lewis is a very impressive young coordinator and play-caller," said Coughlin, who actually attempted to recruit Lewis out of high school. "His presentation when I met with him yesterday was outstanding. He has had great success over the last four years, and I have watched him develop because we competed in the same division. His style will establish toughness and an aggressive style of play."
He originally joined the Steelers staff in 1995, as the defensive backs coach, a position he held for five years before being promoted to coordinator.
Lewis began his coaching career in 1987 at Texas A&M under head coach Jackie Sherrill, who had been his coach at the University of Pittsburgh. He then coached the defensive backs at Southern Methodist from 1989-92, followed by a stint at his alma mater (1993-94).
Lewis was a standout player at Pittsburgh and with the Green Bay Packers, though his career was cut short by injury. He played at Pittsburgh from 1979-82, and was a starting cornerback his final two seasons. Lewis was named an NEA All-America in 1982 and was named the Defensive MVP of both the Senior Bowl and the East-West Shrine games following his senior season. He received an economics degree from Pittsburgh in 1983.
In 1983, the Packers chose Lewis with the 11th overall selection in the NFL draft. Lewis played 52 games for the Packers, twice led or shared the team lead in interceptions and finished his career with 16 picks. His 99-yard interception return for a touchdown against the Rams in 1984 is still the Packers' team record.
But in the third game of the 1986 season, a Monday night contest against the Chicago Bears in Lambeau Field, Lewis suffered a career-ending neck injury. He began his coaching career the following year.
Len Pasquarelli is a senior NFL writer for ESPN.com.