A device for retrofitting an existing trimmed recessed lighting fixture for installation of a trimless recessed light fixture may include a collar section configured to be received within an opening of a housing of the existing trimmed recessed lighting fixture installed above a ceiling surface, the collar section including a proximal section configured to be fitted within the opening of the housing; a surface being secured the collar section, the surface being configured to lie flush against the ceiling and to be joined integrally to the ceiling; and a baffle being releasably lockable to the collar section. A kit including the device and a method of retrofitting an existing trimmed recessed lighting fixture are also disclosed.