The 27-year-old was released by the Baltimore Ravens and suspended indefinitely by the league, as new video emerged on Monday highlighting the violence of Rice's assault on his wife earlier this year in an Atlantic City hotel.
Knighton wrote on Twitter: "That man should be thrown out the NFL and thrown into jail. Shame on those deciding his punishment. Smh. If there's any way to open that case up and give this guy the punishment he deserves, it NEEDS to be done.
"As players we must speak up. Stand up for what's right. I don't give a damn who you are or how much money you make. No place for this. This video makes me sick to my stomach."
Rice joined the league in 2008 when he was drafted by the Ravens.