Incognito, who was released by the Rams on Tuesday, was claimed by the Bills on Wednesday.
The Miami Dolphins also put in a waiver claim for him, but Buffalo was awarded his services because it has a worse record.
Listed at 6-foot-3 and 324 pounds, Incognito is a five-year player who was selected by St. Louis in the third-round of the 2005 draft out of Nebraska.
A starter since his second season, Incognito's fiery style of play eventually got him into trouble. The last straw for the Rams came Sunday, when Incognito was benched in the second half of a 47-7 loss to the Tennessee Titans after the guard drew two personal foul penalties for head-butting.
Named the dirtiest player in the NFL earlier this year by The Sporting News, Incognito was also benched after drawing two personal foul penalties in a season-opening 28-0 loss at Seattle. Last season, Incognito criticized the team's dwindling fan base, made an obscene gesture to a TV cameraman during practice and encouraged hecklers by cupping his hands to his ears while leaving the field after a loss.
The Bills' claim wasn't met with enthusiasm from all members of the team. Injured linebacker Kawika Mitchell criticized the move on this Twitter account.
"BIGGEST DISAPPOINTMENT THIS YR. THE GUYS A BUM. DIRTY AND ALWAYS WILL BE. REALLY WISH I WAS PLAYIN RITE NOW. SERIOUSLY... I KNO WE'RE N NEED OF OLINE BUT THIS GUY [stinks]," Mitchell wrote.
Mitchell later wrote on Twitter that he regretted that his comments were made in public.
"I said what I said bout iggy and it's over. Everything else will b handled n house," he wrote.
Incognito is still considered a solid run-blocker, who started 44 games with the Rams.
The move comes as the Bills (5-8) prepare to host the New England Patriots (8-5) on Sunday and marks Buffalo's latest attempt to address a banged-up line that could be down yet two more regulars.
Tackle Jonathan Scott didn't practice Wednesday after sustaining an eye injury in a 16-10 win at Kansas City last weekend. Guard Kendall Simmons, who was thrust into the starting lineup days after being signed three weeks ago, also missed practice with a shoulder injury.
The Bills haven't had a healthy front five all season and now have three starters on injured reserve after left tackle Demetrius Bell was placed on the season-ending list last week.
It's unclear when Incognito will join the Bills.
Rams coach Steve Spagnuolo called it a difficult decision to release Incognito but noted he felt it was a move "made in the best interest of the football team, and I do think it's good for both parties."
Spagnuolo added: "I've got a lot of respect for Richie. I like him a lot. I wish him the best."
Information from ESPN NFL Insider Adam Schefter and The Associated Press was used in this report.