The Cherries have re-signed the 27-year-old striker from Norwich City for a fee believed to be in the region of £7million after they sold him to the Canaries back in 2014.
Grabban scored 12 goals for the Canaries in the Championship last year but struggled to hold a regular spot in Alex Neil's first team this season and now finds himself back in Dorset much to the delight of Elphick.
"I am absolutely delighted Grabbs is coming back," Elphick told Cherries Player HD.
"He's a great player and also a good pal of mine. Very rarely in football do you stay in touch with people, as cynical as that sounds, but Grabbs is someone I have always stayed in contact with.
"We've got a great bond but, above that, we are signing a quality player. He doesn't need any introduction, the fans know what he is about and so do the players.
"He is all about business and that's why we all got on so well. He loves winning and he inspired us during that first season in the Championship. He ran tirelessly and scored some really important goals for us."