Multiple media outlets reported that Bortles could receive a quick hook if he struggles.
"I spoke to both quarterbacks this afternoon and told them that Blake will be our team's starting quarterback," Jaguars coach Doug Marrone said in a statement. "I believe this gives us the best opportunity to win."
Bortles lost his second fumble and was benched early in the second half of Sunday's 20-7 setback to the Houston Texans. The 26-year-old Bortles had completed 6 of 12 passes for 61 yards against the Texans while Kessler went 21 of 30 for 156 yards with a touchdown and an interception.
Signed to a three-year, $54 million contract extension in February, Bortles has committed 10 turnovers in seven games this season. He has completed 151 of 249 passes for 1,735 yards with nine touchdowns and eight interceptions in 2018.
Bortles will look to turn it around for the Jaguars (3-4), who will play the Philadelphia Eagles (3-4) at Wembley Stadium in London on Sunday.