Controlled light-mediated delivery of biological analytes can enable the investigation of highly reactivity molecules within living systems. As many biological effects are concentration dependent, it is critical to determine the location, time, and quantity of analyte donation. In this work, we have developed the first photoactivatable donor for formaldehyde (FA). Our optimized photoactivatable donor, photoFAD-3, is equipped with a fluorescence readout that enables monitoring of FA release with a concomitant 139-fold fluorescence enhancement. Tuning of photostability and cellular retention enabled quantification of intracellular FA release through cell lysate calibration. Application of photoFAD-3 uncovered the concentration range necessary for arresting wound healing in live cells. This marks the first report where a photoactivatable donor for any analyte has been used to quantify intracellular release.