The network has stated that the upcoming programme will profile people across the US who have intriguing and unusual lifestyles.
First season episodes will feature Pennington visiting a commune and will explore Delta blues culture with the help of Robert Plant and Morgan Freeman.
Pennington said of American Journey: "I've covered a lot of ground across America as host of Extreme Makeover: Home Edition, and seen first-hand the resilience of the American spirit regardless of the heavy burdens and obstacles they've faced.
"I'm happy to be part of American Journey and work with HLN to uncover inspirational stories that will surely have a positive impact on viewers."
American Journey will premiere its ten-episode season on Saturday, January 12, 8-8.30pm ET. Repeats are expected to air throughout the weekend when each new instalment premieres.
Pennington is best known for hosting Extreme Makeover: Home Edition on ABC and appearing on the short-lived daytime series The Revolution.