The Razlan Razali-run outfit, which was rebranded as RNF Racing in 2022 following Petronas SRT's exit at the end of last year, will sever ties with Yamaha at the conclusion of the current campaign.
RNF will field year-old Aprilia machinery next year, with outgoing KTM riders Oliveira and his Tech3 counterpart Fernandez refreshing the team's line-up for 2023 having signed two-year deals.
Oliveira has long been linked to RNF having turned down a move back to Tech3 by KTM, while rookie Fernandez negotiated an exit from his deal with the Austrian marque recently to join RNF.
Fernandez originally wanted to join RNF's predecessor Petronas SRT for his rookie campaign until KTM locked him into a contract to race for Tech3.
RNF's current line-up will depart MotoGP at the end of the season, with Andrea Dovizioso retiring at the end of this weekend's San Marino Grand Prix, while Darryn Binder looks set to move to Moto2, having stepped up to the premier class directly from Moto3.
RNF boss Razali says signing its two new riders was "not a simple process", but both the team and Aprilia "believe in the talent of both riders".
"We are extremely excited to welcome Miguel Oliveira and Raul Fernandez to the WithU RNF MotoGP Team from 2023," Razali said.
"It has not been a simple process, but together with Aprilia we are very clear on the riders that we wanted.
"They are both young riders with a good combination of experience coming from Miguel and Raul who I'm personally a fan of since he shocked the Moto2 category last year to become Vice Champion. To finally secure him, is fantastic.
"Both, Aprilia and we believe in the talent of both riders, so we can't wait for them to ride for us next season!"
Oliveira's place at KTM has been taken by Jack Miller, who in turn will be replaced by Enea Bastianini at the factory Ducati squad.
Tech3, which will be rebranded as GasGas Factory Racing in 2023, will welcome back Pol Espargaro from Honda, while reigning Moto2 champion Remy Gardner suggested during the Austrian GP weekend that he will not be with the team next year.
Moto2 frontrunner Augusto Fernandez, who races for the KTM-backed Ajo Motorsport, is linked to the seat alongside Espargaro at Tech3.
Earlier on Tuesday morning, Honda finally announced it had signed Joan Mir on a two-year deal to join its factory team alongside Marc Marquez in 2023.
