DeChellis replaces Billy Lange, who left Navy to become the associate head coach at Villanova.
"It's been a very, very dificult weekend for me and my family. If I break down, there's good reason for that," DeChellis said during a 20-minute news conference at the Jordan Center. "Penn State is a special place for me and my family, but I found another special place in the U.S. Naval Academy."
He goes from a power conference school to a program that plays in the brainy Patriot League. DeChellis took the job on Sunday.
"It was very, very difficult. At Mass yesterday, father talked about a path. Sometimes a path is presented to you that you have to be able to walk down," he said before stopping to compose himself before nearly tearing up.
DeChellis leaves a BCS school and member of the Big Ten for Navy, arguably one of the more difficult jobs in college athletics given its admissions and post-graduate service requirements as a military academy.
In the final season at his alma mater, DeChellis took Penn State to the NCAA tournament for the first time in 10 years. The Nittany Lions (19-15, 9-9 Big Ten) lost to Temple in the second round.
"On behalf of the Penn State and State College communities, I would like to offer my sincere appreciation to Ed DeChellis and his staff for their efforts with the men's basketball program the past eight years," Penn State athletic director Tim Curley said in a statement. "Ed and his staff built a strong foundation for the program and then were able to see all their tireless efforts result in winning the 2009 NIT Championship and advancing to the Big Ten Tournament championship game and the NCAA Tournament this past season."
Pressure had been mounting steadily on DeChellis in recent years. In eight years at Penn State, DeChellis put together a 222-232 record. He was given a three-year extension in 2009, after the Lions won the NIT title.
Multiple sources close to DeChellis said he was told prior to last season that he would be fired if the Nittany Lions didn't make the NCAA tournament. Penn State did earn a No. 10 seed and lost to Temple in the second round of the NCAA tournament.
When DeChellis returned he expected to receive some sort of assurances that he would be protected going forward after making the NCAAs. But that didn't occur and no extension was offered again. A source said DeChellis met with Navy athletic director Chet Gladchuk over the weekend and accepted a long-term contract with the Naval Academy.
"To have one of the most highly respected coaches and educators in the sport join our Navy family is a great day for the program and the Academy," Gladchuk said in a statement. "Ed's maturity, integrity, character and accomplishments at Penn State have made him one of the most respected role models in the coaching ranks. His career is all about building programs with educational priorities in place, including graduating every senior that has ever played for him, and in the end achieving team goals that resonate with competing for championships. Ed will make a positive and impactful impression on Navy Basketball in short order."
The Nittany Lions signed a five-player recruiting class for the fall and are counting heavily on Dayton transfer Juwan Staten to help Penn State in a major rebuilding year. Staten will be forced to sit out a season and won't be able to contribute until the 2012-13 season.
DeChellis suspended sophomore guard Taran Buie earlier in the season and he elected to transfer after the season. Buie is Battle's younger brother.
A number of sources said the Nittany Lions will have a hard time recruiting an existing high-major head coach for the position based on the current state of the program and the timing of the opening.
Dana O'Neil covers college basketball for ESPN.com. Information from ESPN.com's Andy Katz and the Associated Press was used in this report.