The swelling of manufacturer involvement in the WEC's Hypercar class means there is no room for LMP2 next season, prompting category stalwart United to enter IMSA on a full-time basis.
The 2020 Le Mans 24 Hours LMP2 class-winning team has made select North American outings in recent years alongside programmes in the WEC and European Le Mans Series, recording a best result of third at Watkins Glen in 2021.
Unlike in the WEC, LMP2 teams in IMSA are obliged to run a bronze-graded driver. United team co-owner Richard Dean said the signing of 2021 IMSA P2 champion Keating and promising Briton Quinn was "a show of intent".
"We are all very motivated to be working with these talented and proven winners in IMSA," he said.
"We are coming to IMSA to win races and having Ben and Alex join our team gives us every chance of achieving that.”
Keating wrapped up the WEC's GTE Am title for Corvette Racing at Monza in July, shortly after taking his second class victory at Le Mans the previous month. He also completed a Le Mans GTE Am/WEC title double with the TF Sport Aston Martin team in 2022.
The Texan has kept his hand in racing prototypes alongside his GT exploits too, and currently leads the points alongside full-time team-mate Paul-Loup Chatin for PR1/Mathiasen Motorsports.
Silver-rated Quinn, a race-winner against current Formula 1 drivers Oscar Piastri and Logan Sargeant in the 2017 British Formula 4 championship, switched to sportscars this season and has made three appearances alongside Keating in the endurance races.
"I have been with PR1 for the past three years and we have seen an enormous amount of success, but I am really excited to complete the full 2024 IMSA season with United Autosports," said Keating.
"Working with Alex Quinn in 2023 has been great and I believe he will continue to develop even more under the United Autosports banner."
Keating also voiced an interest in racing at Le Mans with United next year with a minimum of 15 entries set to be guaranteed from IMSA, the ELMS and Asian Le Mans Series.
He has previously made two Le Mans starts in LMP2, the most recent coming in the only European outing for the unloved Riley Mk. 30-Gibson in 2017.
"Running in the 24 Hours of Le Mans for a 10th time in a row is a big priority for me," Keating added.
"I'd like to attempt to win my class for a third year in a row, and I believe United Autosports gives me the best chance at realising this goal."
