Leeds are expected to make a significant profit on the Finnish international, who only joined the club last summer in a deal worth between £4m to £5m from Scottish giants Rangers.
Rennes are set to pay around £8m for Kamara, who was an active target 12 months ago before he opted to head to West Yorkshire.
Kamara has travelled to France to undergo medical and a deal could go through on Tuesday evening.
Kamara’s departure follows the exit of Archie Gray to Tottenham Hotspur, although United have brought in one fresh option in the middle of the park in the shape of Bournemouth loan midfielder Joe Rothwell, with the Championship club also in the market for other targets in the engine room.
Meanwhile, Leeds are maintaining their interest in Sheffield United right-back Jayden Bogle, despite seeing a couple of initial offers rebuffed by the South Yorkshire club.
Denmark full-back Rasmus Kristensen is due to back to training at Thorp Arch on Friday alongside Austrian international Max following Euro 2024 duties, with Bundesliga outfit Eintracht Frankfurt having reportedly made a move for the former.
The Blades beat off interest from both the Premier League and MLS to sign in-demand attacking midfielder O’Hare from Coventry City.
The 26-year-old reportedly turned down an extremely lucrative offer from the US and also had interest from the likes of Leicester City and Southampton, newly promoted to the Premier League, and relegated .