Johnson suffered a sprained MCL in his left knee Sunday, coach Bruce Arians said during his season-ending news conference Monday, but did not suffer any tendon damage and will not require surgery.
When the injury initially occurred, Johnson laid on the ground and feared the worst-case scenario. But he will just require six to eight weeks of "rest and rehab."
"That's great news," Arians said.
Johnson was injured late in the first quarter of the Cardinals' 44-6 win against the Los Angeles Rams after he was tackled for a 3-yard loss. He was helped off the field and eventually carted to the locker room but was standing on the Cardinals' sideline during the second half. When Johnson met with reporters Monday, he was wearing a bulky knee brace on his left leg.
Johnson said he was "scared" after going down, but once the pain from the initial hit subsided and the shock wore off, he realized his injury wasn't as serious as he thought -- or as it could've been.
"A lot of relief," Johnson said. "A tremendous amount of relief to know that there is nothing damaging, no significant injury. I was very proud that my knee is strong enough and those ligaments are strong enough that it prevented me from having a serious thing."
By the time Johnson had an MRI, he was confident he didn't suffer a major injury.
"I actually wasn't worried at all," he said. "It felt strong, even in walking.
"I think I was just scared at first (after) the initial contact. But after I calmed down a little bit, got in the locker room, I was fine."
After seeing the replay, Johnson said he was "definitely blessed" the injury wasn't more serious. He said "probably a little bit of everything" contributed to his knee holding up, counting his faith, luck and his training as factors.
Because of his recovery and rehabilitation timeline, Johnson said he will not play in the Pro Bowl on Jan. 29. With his wife due to give birth to their son on Jan. 27, Johnson won't face the dilemma anymore of where he'll be and when.
"We were joking around about that," Johnson said. "Unfortunate that it happened. I'm definitely going to be glad to be there. I was always going to be there for the birth. Unfortunate that it happened like that, but I'm definitely going to be happy to be there."