"I just got offered by Mississippi State," Johnson told JCFootball.com.
The offer from the Bulldogs joins the four he previously had from Arkansas State, Nebraska, Central Florida and West Virginia.
Johnson is also hearing from Ole Miss, Houston and several other FBS programs.
"I'm working on setting up visits with Nebraska and Houston right now," Johnson said.
As a freshman last season for the Golden Norsemen, Johnson posted 53 tackles, three sacks, five tackles-for-loss, one forced fumble, one fumble recovery and an interception from his defensive tackle spot.
"I am around the ball a lot," Johnson said. "I figure if you're around the ball a lot, you have the chance to make plays. I study a lot of film and I have a quick first step and that helps me get to where I need to be and to beat the man in front of me.
"I'm working a lot on my footwork, just trying to be as quick as possible, and I want to get faster in my takeoff so that I can be even more of a factor in rushing the quarterback."
As a prep at Northside High School in Warner Robins, Georgia, Johnson was getting some attention from schools, but he was unable to qualify.
"The coaches here were great and really it was a family decision for me," Johnson said. "I just needed to get to a place that could help me get ready for the next level and be a place where I could focus just on football and school."
Johnson is on pace to finish up his academic work in December and he will have three years to play two following the 2016 football season.
Isaiah Johnson Scout Profile