The British world heavyweight champion will be targeting his 20th straight victory against Pulev at the Principality Stadium on October 28, live on Sky Sports Box Office, but why has 'AJ' opted to face this Bulgarian opponent?
Joshua then had no option but to fulfil his mandatory title defence against the IBF's No 1 challenger Pulev.
If 'AJ' selected a different opponent, then he would have been stripped of the IBF belt which he had won last April against Charles Martin.
Joshua added the WBA 'super' title to the IBF belt after his win over Klitschko and was last month ordered by the WBA to face mandatory challenger Luis Ortiz.
But the IBF defence was the more pressing issue, with an agreement already in place for Pulev to receive the next title shot.
Promoter Eddie Hearn is hoping to reach a resolution with the WBA, allowing Joshua to fulfil his IBF title duties against Pulev before facing Ortiz in his first fight of 2018.
"Obviously we now have to fight Pulev and Ortiz and it's going to be a tough balancing act," said Hearn. "The Pulev mandatory was called some time ago and we already have signed correspondence that if it's not Klitschko then Pulev must be next.
"I would say right now the plan is Pulev, Ortiz then if [Deontay] Wilder still has a belt then AJ can relieve him of that next summer."
No. Hearn recently confirmed a ruling by the IBF, stating "after the rematch there will be no request for a unification considered by the IBF."
WBC champion Deontay Wilder had previously called for a clash against Joshua, with three world titles at stake, but the American is now thought to be lining up a fight against Ortiz.
Joseph Parker holds the WBO belt and is a potential future opponent for Joshua, although the New Zealander cannot commit to a fight until he defends his belt against Hughie Fury on September 23.
'The Cobra' has claimed 25 victories, with 13 knockouts, and his sole defeat came in the form of a fifth-round knockout against Wladimir Klitschko in 2014.
Pulev regained his lofty placing in the IBF rankings with five successive wins, including a points victory over Dereck Chisora.
He also holds wins over former WBC champion Samuel Peter and world title challengers such as Tony Thompson and Kevin Johnson.
This is a perilous assignment for the 27-year-old as his ambitious plans could be ripped up by a dangerous challenger.
Joshua admits he is still a work in progress, despite his perfect 19-fight record, and Pulev will be eager to exploit any lingering defensive vulnerabilities.
Pulev is vastly more experienced, with his pro debut coming eight years ago, and packs a stinging jab and enough power to seriously trouble the champion.