Harlequins prop Marler last featured for England against South Africa in June 2018 before retiring due to personal reasons, but he has now reversed that decision.
Gloucester's Willi Heinz has won the battle for inclusion at scrum-half, with Saracens' Ben Spencer also included, but Wasps' Dan Robson missing out.
England boss Eddie Jones said: "I saw Joe during the Barbarians' week and he indicated that he had a desire to come back.
"We have since had a couple of chats and we have given him the opportunity to do that. Now it is up to him to show us what he has got.
"We can't wait to have the full squad in place and to have players competing for those (final World Cup) 31 places.
"It is a process of building the team up, building the cohesion, the tactical understanding of the team and our adaptability. We will need to get those things right to win the World Cup, and that is our aim."
Gloucester fly-half Cipriani won the Premiership player of the year and players' player of the year awards in a sterling first campaign with the Cherry and Whites.
Now the 31-year-old has the chance to push for a final World Cup place.
Harlequins prop Kyle Sinckler has been included after a hamstring injury scare.
Harlequins full-back Mike Brown has missed out, while Saracens' Alex Lozowski has also been overlooked.
The continued absence of Dylan Hartley due to knee injuries leaves the former captain unlikely to make the autumn's World Cup.
Jones said: "World Cup selection is a four-year process. We have looked at the squad carefully, tried to build up a squad that has enough experience, attitude and energy to be winners and I think we have that.
"In the process, we have left out some players who can feel unlucky. For those guys who have missed out, the door is never closed but they have just got to be ready, as you never know when the opportunity comes."
England must submit their final 31-man World Cup squad on September 2, and they start their campaign against Tonga in Sapporo on September 22.
Jones added: "For the fans it is the start of the journey, so we want you to be with us, we are all in this together."
