Carpenter, 25, rode for the Hincapie-owned Continental team since 2013, winning multiple national calendar events along with stages at the Tour of Utah, the USA Pro Challenge and the overall victory at the 2016 Tour of Alberta.
"I'm always trying to push myself as a rider and never settling for a result," Carpenter said in a statement released with the team's announcement.
"Rally is one of the most professionally run programs in America, and their two-year commitment to me was a huge draw," he said. "I had some great years on Holowesko-Citadel and I am thankful for their support. Right now I am looking forward to this next step in my career."
Carpenter scored his first major win at the 2015 USA Pro Challenge, soloing into Crested Butte on a wet and wild day. He added a stage win at the Tour of Utah in 2016 and then followed that up with the overall win at the Tour of Alberta.
In 2017, Carpenter won a stage at the San Dimas Stage Race, then took the overall win at the Joe Martin Stage Race with a daring attack in the rain on the final day. He won the one-day Winston-Salem Classic in June and the points classification at the Tour de Beauce.
"When Robin shows up to a race you immediately have to account for him in your race strategy," said Rally Performance Director Jonas Carney. "He's that dynamic. Signing him was at the top of our list as we thought about the areas of our program that we needed to improve."
Carpenter started the second half of the 2017 season by taking the overall win on the final day of the Cascade Cycling Classic, and his form appeared to be on the rise at the Tour of Utah before injuries suffered in a crash during stage 5 ended his season and prevented him from defending his Alberta title.
With Rally hoping to move to the Pro Continental level next year, Carpenter can count on even more racing over the next two seasons.
"The road season gets longer every year," said Carney. "We used to start racing in March and now we are planning a Europe trip for the beginning of February. This extended season gives riders like Robin the time to find their place within the team and plenty of opportunity to start big races and aim for success."
Aside from a longer season and increased opportunities to compete in Europe, Carpenter said he's excited to race alongside experienced Rally veterans like Danny Pate, who rode on WorldTour teams for eight years before joining Rally in 2016.
"Having riders like team captain Danny Pate to learn from will be amazing," Carpenter said, indicating that Pate, who is in the second year of a two-year deal, may extend his current contract and return for at least one more season.
"Good positioning, tactics and instincts on the road are vital when racing in Europe, Carpenter said. The racing rewards aggressiveness and keeps you on your toes. In the US, the roads are bigger and you have more time to make a decision, while in Europe it is the opposite."