It will be Ambrose's third season for RPM in the No. 9 Ford and Almirola's second in the No. 43 made famous by co-owner Petty.
Ambrose will be sponsored by Stanley and DeWalt. Almirola will be sponsored by Smithfield Foods and its family of brands.
"It's good to come back to Richard Petty Motorsports and focus on our future together," said Ambrose, who will start Sunday's finale at Homestead-Miami Speedway second. "We had success this year and recently have made plans to get better for 2013 and beyond.''
Almirola, in his first Cup season, has shown progress lately with a fourth-place finish at Martinsville and an average starting position of 7.8 over the last five races. He will start fifth Sunday.
"We went through some changes this season, but since being paired with Todd [Parrott] and this crew, I've had the most fun I've had in a Cup car," Almirola said. "We have a lot of things clicking right now and have a lot of momentum heading into 2013.''
RPM previously announced its continuing relationship with Ford Racing and the addition of crew chief Drew Blickensderfer.
"We have shuffled our Cup team lineups a few times this season to maximize our results," competition director Sammy Johns. "We feel that the chemistry that we are developing now with both teams is very strong. We have seen marked improvement over the past few weeks.''