The purpose of this article is to evaluate the effectiveness of collagen crosslinking of filtering blebs with 0.1% riboflavin stimulated with ultraviolet A radiation in a case of a thin-walled filtering bleb with leakage following an episode of late blebitis. The time to cessation of the bleb leakage was studied, as well as the intraocular pressure, the visual acuity, and the presence of adverse effects during 4 years of follow-up after treatment. A single session of crosslinking was effective in resolving the leakage of the filtering bleb. There were no adverse effects. The intraocular pressure and the visual acuity remained stable after 4 years of follow-up. Collagen crosslinking with 0.1% riboflavin stimulated with ultraviolet A radiation may prove to be a simple, painless, non-invasive, and repeatable treatment of the leaking bleb with the aim of strengthening the collagen fibers of the conjunctiva and avoiding more invasive surgical treatments.