Hamilton announced his intention to begin a new chapter at the start of this season having been frustrated by the team's inability to challenge Red Bull at the top of the order.
And Hamilton's demise during that spell opened the door for Max Verstappen to cement his status as the sport's dominant force.
The Dutchman has won each of the last three titles, and following his stunning win in Brazil last weekend, is all but guaranteed to add another championship to his collection in 2024.
Hamilton will be hoping his upcoming transfer to Ferrari will enable him to once again challenge for race wins on a consistent basis as he looks to take Verstappen's crown.
Speaking to talkSPORT, Horner insisted the 105-time race winner is more than capable of offering a substantial challenge to his star man next year, reigniting the pair's bitter 2021 rivalry.
"He's obviously coming out of a very comfortable environment, one that he knows very well over the last 10 years, more than 10 years," he said. "So that'll be a change for him.
"Charles Leclerc is another very fast driver. But Ferrari is a team that looks like they're picking up momentum. For sure, a driver of Lewis' quality is always going to be a challenger.
"He could be just jumping at the right time. He's obviously seen things that he's chosen to change teams for because he believes in the future of Ferrari, so that's going to be fascinating to see how that plays out."