As expected, Messi, 30, re-signed with the LaLiga giants on Wednesday, putting pen to paper on a deal until 2021.
Neymar was thrilled with the Argentina international's extension, which puts Messi on track to finish his career at Barca.
"I'm very happy to have the best in the world with us," he said.
"It's complicated to think about football without him."
Under a new coach in Ernesto Valverde, Barca are preparing for what is sure to be another title battle with rivals Real Madrid in 2017-18.