The 20-year-old will partner Cameron Hill in the #35 MSR Camaro for the Sandown 500 and Bathurst 1000 later this year.
Confirmation of the deal follows Robotham's test with MSR at Queensland Raceway last Thursday and completes the squad's line-up, with Jayden Ojeda locked in alongside Jack Le Brocq.
The enduro drive will sit alongside a packed programme for Robotham this year that includes Trans Am in Australia and the Super Series Super Pickup category in Thailand.
It will mark his second Great Race start after he partnered Matt Chahda in the Matt Chahda Motorsport wildcard at Bathurst last year.
“[I'm] really excited to be joining Cam and MSR in the #35 Truck Assist Camaro for the enduro rounds this season,” said Robotham.
“We had a decent test last week and it felt good with the team.
“Having worked with [engineer] Paul Forgie before and also having done my first evaluation day with MSR a few years ago really made it a lot easier coming into the team.
“I can’t thank everyone enough that made this possible and also to everyone at MSR for this opportunity.”
Team owner Matt Stone welcomed Robotham to the squad.
“We are pleased to welcome Jaylyn into the MSR family,” said Stone.
“Already Jaylyn is immediately fitting in well with the team, and having worked with Paul Forgie in the past, that has sped up the process.
“He did a good job in the Caltex wildcard last year in difficult conditions and has proven he can drive around Bathurst in a decent lap time with no mistakes over a six-hour race.
“Cam and Jaylyn are a good, young combination and Jaylyn will perform his role as a co-driver very well for car #35.”
The Robotham deal leaves just two seats on the enduro grid unconfirmed – the single Blanchard Racing Team entry and the #23 PremiAir Camaro.
Kurt Kostecki tested with PremiAir last week and is the favourite to partner Tim Slade should Joey Mawson not be awarded a Superlicence.
Mawson has been offered the seat but, having not raced in Super2, technically isn't eligible for a Superlicence.
Supercars has indicated it won't budge on the requirement, leaving an FIA rating upgrade as Mawson's only hope.
2023 Supercars endurance field
| # | Team | Primary Driver | Co-driver |
| 2 | Walkinshaw Andretti United | Nick Percat | Fabian Coulthard |
| 25 | Walkinshaw Andretti United | Chaz Mostert | Lee Holdsworth |
| 3 | Blanchard Racing Team | Todd Hazelwood | TBA |
| 4 | Brad Jones Racing | Jack Smith | Jaxon Evans |
| 8 | Brad Jones Racing | Andre Heimgartner | Dale Wood |
| 14 | Brad Jones Racing | Bryce Fullwood | Dean Fiore |
| 96 | Brad Jones Racing | Macauley Jones | Jordan Boys |
| 5 | Tickford Racing | James Courtney | Zak Best* |
| 6 | Tickford Racing | Cameron Waters | James Moffat |
| 55 | Tickford Racing | Thomas Randle | Garry Jacobson* |
| 56 | Tickford Racing | Declan Fraser | Tyler Everingham* |
| 9 | Erebus Motorsport | Will Brown | Jack Perkins |
| 99 | Erebus Motorsport | Brodie Kostecki | David Russell |
| 11 | Dick Johnson Racing | Anton De Pasquale | Tony D’Alberto |
| 17 | Dick Johnson Racing | Will Davison | Alex Davison |
| 18 | Team 18 | Mark Winterbottom | Michael Caruso |
| 20 | Team 18 | Scott Pye | Warren Luff |
| 19 | Grove Racing | Matthew Payne | Kevin Estre* |
| 26 | Grove Racing | David Reynolds | Garth Tander* |
| 23 | PremiAir Racing | Tim Slade | TBA |
| 31 | PremiAir Racing | James Golding | Dylan O’Keeffe |
| 34 | Matt Stone Racing | Jack Le Brocq | Jayden Ojeda |
| 35 | Matt Stone Racing | Cameron Hill | Jaylyn Robotham |
| 88 | Triple Eight Race Engineering | Broc Feeney | Jamie Whincup |
| 97 | Triple Eight Race Engineering | Shane van Gisbergen | Richie Stanaway |
| 888 | Triple Eight Race Engineering | Craig Lowndes | Zane Goddard |
