Sources told ESPN.com that Walker will receive a four-year, $48 million extension from the Hornets that will kick in starting with the 2015-16 season.
The sides were facing a Friday deadline to finalize a deal to prevent Walker from becoming a restricted free agent in July.
Walker joins Cleveland's Kyrie Irving, Denver's Kenneth Faried, Orlando's Nikola Vucevic and Phoenix Suns twins Markieff and Marcus Morris as extension recipients since the window for such deals opened July 1.
By securing Walker's services, Charlotte avoids the uncomfortable prospect of seeing two of its top players hit the open market in July. Hornets center Al Jefferson has the right to become an unrestricted free agent this summer.
"You are always concerned -- more so with Al because he's totally unrestricted," Hornets owner Michael Jordan told The Observer.
"They are core pieces of what we're trying to do ... I'd like to keep both of those guys. I say I'd like to and I'd spend the money that's appropriate. I'll make every attempt to keep them."
Walker helped recruit Jefferson to Charlotte in the summer of 2012, when the former Utah Jazz big man signed a three-year deal worth nearly $41 million. The Hornets then signed Lance Stephenson away from the Indiana Pacers this past summer on a three-year deal worth nearly $28 million.