"I've been advised that the stresses and anxiety of this job do not match up some of my cardiac issues," Tedford said in a news conference on Friday.
The former head coach said his resignation is "solely to do with health;" he will take time to recoup and to focus on his family.
Tedford underwent an emergency procedure where his heart was shocked back into rhythm after visiting his cardiologist with symptoms he felt "weren't normal" during practice three weeks ago. The players were not informed of the procedure and Tedford traveled to Nevada for the Bulldogs game against the University of Nevada.
He will have an ablation in January at the Mayo Clinic to help ease some of the issues.
"My wife and sons have sacrificed a lot, and now it's time to live," he said.
Tedford just wrapped up his third season as head coach. A quarterback at Fresno State in the early 80s, he returned to the university in 2017.
The Bulldogs were coming off a one-win season. In Tedford's first year at the helm, the Dogs won ten games and made it to the conference championship. It was the biggest two-year turnaround in college football history.
The following year, he led Fresno State to the winningest season in program history with a Mountain West title in Boise followed by a win in the Las Vegas Bowl, capping a 12-2 year. The Bulldogs finished the season ranked 18th in the country.
RELATED: Timeline of Jeff Tedford's football career that spanned several decades
"I'm very thankful for the last three years to be able to come back to my alma mater and to be connected with the university, with the players, the coaches, the great Fresno community, which I've always loved," he said.
While the 2019 season was not what was expected of the Bulldogs, Tedford said the season brought plenty of lessons, and he is proud of the players' academic success.
WATCH: Tedford's proudest moments with the Bulldogs
The announcement came as a shock to the players, Tedford said, but he was met with hugs and handshakes from each team member.
Tedford assured his resignation is not farewell to the Fresno State community. He said he would continue to be "a resource" to Athletic Director, Terry Tumey, and the athletics department.
"Whatever I can do to help the program, the university, I'm here to do that," he said.
Though a replacement has not been announced, offensive coordinator and associate head coach, Ryan Grubb, will sit in as the interim coach until there is a hire.
Tumey said the process to find a new head coach has begun, but a hire will not be announced until after a 14-day waiting period mandated for the California State University system. There is a concern for future recruits, as signing day is scheduled for Dec. 18.
"I think I am well-equipped and ready to be able to find the next person to try to lead this program in the way that Jeff Tedford did," Tumey told the media Friday. "We feel as though these young people need to understand who their leader is going to be to continue down the path of development."
Tedford said he had confidence in the team and encouraged them to stick together.
"Everything is going to be fine; they're going to be fine. There's a lot of talent in that room and the future is bright," he said. "To always reach for their full potential in whatever they do, and to continue to do it with class and integrity and to always uphold the pride and tradition of Bulldog football."
WATCH: Tedford's message to the Bulldogs