Brown joins the team with more than 40 years of experience in motorsport, highlighted by a spell with Williams in F1.
Brown has joined JHR as its technical director, replacing Yves Touron.
The F1 veteran worked with the likes of Ayrton Senna, Nigel Mansell, Alain Prost, Damon Hill, Thierry Boutsen, and David Coulthard at Williams.
Brown also worked with the McLaren junior team and Jordan with Heinz-Harald Frentzen before pivoting to sports car racing in North America.
According to JHR, Brown will oversee the technical department and work closely with engineering staff, drivers, and management – putting F1 practices into play.
“I’m delighted to accept this opportunity and look forward to working with the team,” said Brown.
“The IndyCar Series is fiercely competitive, and it’s a challenge I am ready to embrace.”
Team co-owners Ricardo Juncos and Brad Hollinger hailed the arrival of Brown.
“I believe the wealth of knowledge and perspective that David brings will help us fight our way up the grid during the 2025 INDYCAR season,” said Juncos.
“I would also like to take this opportunity to acknowledge the incredible contributions that Yves Touron has made to JHR.
“His expertise and professionalism have been truly unparalleled. We wish him all the best in his future endeavours.”
Hollinger added, “I’m excited to welcome David to Juncos Hollinger Racing.
“His presence reinforces our commitment to continued advancement on the technical side of the team.
“His vast experience in F1, as well as other forms of motorsport, will benefit the team from day one.
“I also want to thank Yves for his significant contributions to JHR and wish him a fulfilling and prosperous future.”
The signing could prove pivotal for the ailing IndyCar team.
The team went through four drivers in 2024. Romain Grosjean was a constant at the team in the #77 while the #78 was primarily led by Agustin Canapino.
Canapino was dropped briefly in favour of Nolan Siegel before being replaced by Conor Daly for the final five races of the year.
JHR has already announced Sting Ray Robb will pilot the #78 in 2025. The driver of the #77 is yet to be confirmed.
Grosjean’s future at JHR is yet to be announced. The Frenchman cast doubt over his place at the team, citing funding issues.