Walcott has also been coaching her compatriot Shelly-Ann Fraser-Pryce since the 2020 season.
The two sprinters have seemingly maintained a consistently frosty relationship.
Andi Sports Management, Thompson-Herah's agency, stated on Thursday that the separation from Osbourne resulted from a "breakdown in negotiations on a compensation package" sought by Osbourne.
Thompson-Herah and Walcott begin their collaboration less than a year before she defends her 100-meter and 200-meter titles at the Paris Games.