Like Winterbottom and Mee, Josh Dasilva is also off contract on June 30, but will be allowed to use the club's facilities as he works his way back from a knee injury suffered in January 2024.
Goalkeeper Winterbottom joined the Bees in 2021 from Liverpool and was added to the senior squad this past season.
He spent the campaign in the National League on-loan with Fylde.
Meanwhile, Mads Roerslev (Wolfsburg), Frank Onyeka (Augsburg), Myles Peart-Harris (Swansea City), Matthew Cox (Crawley Town), Jayden Meghoma (Preston North End), Ellery Balcombe (Motherwell) and Ryan Trevitt (Exeter City) have all returned to Brentford from their respective loans.
Regarding the club's B squad, Michael Olakigbe (Chesterfield Town), Tony Yogane (Exeter), Ashley Hay and Val Adedokun (both at Cheltenham Town) have also returned from their loans.