Lombardi, grandson of Hall of Fame coach Vince Lombardi, emerged as the favorite among numerous candidates for the job since Jim Caldwell was hired last week as coach, sources told ESPN.
The Lions were finalizing a contract with Lombardi on Tuesday morning, according to sources.
Lombardi spent the past seven seasons as an offensive assistant with the Saints, who promoted him to quarterbacks coach in 2009.
With New Orleans, Lombardi helped oversee a high-powered offense led by eight-time Pro Bowl quarterback Drew Brees, who has passed for more than 5,000 yards in each of the last three seasons.
Lombardi will be counted on to mentor Lions quarterback Matthew Stafford, who struggled during Detroit's late-season collapse in 2013.
Lombardi was a tight end at Air Force from 1991 to 1993 and also played lacrosse for a season at the school. As a coach, he bounced around the lower levels of college football at Dayton, Virginia Military Institute, Bucknell and Mercyhurst College, where he was the offensive coordinator from 2002 to '05. He also coached in the XFL before landing with Atlanta as an defensive assistant in 2006.
At Mercyhurst his final two seasons as the offensive coordinator, his teams averaged around 22 points a game. In 2004, Mercyhurst averaged 271.3 yards of offense per game, and in 2005, the team averaged 348.9 yards of total offense.
It is unclear who will call plays for Detroit this season. Caldwell, who spent parts of the last two seasons as the Baltimore Ravens' offensive coordinator, has left open the option of calling plays himself.
ESPN.com Lions reporter Michael Rothstein contributed to this report.