BACKGROUND: Tranexamic acid (TXA) is a promising active to treat hyperpigmentation disorders, such as melasma and acne scars. However, TXA is highly hydrophilic and its penetration into the skin is poor and formulation dependent. AIMS: In this study, our aim was to evaluate the in vivo skin penetration of an ester-modified TXA, TXVector, directly on the skin of volunteers. METHODS: For the analysis of in vivo skin penetration of TXVector, we used in vivo confocal Raman spectroscopy (CRS). The use of CRS on live skin allows us to study directly how a compound affects skin composition at different depths and how this compound penetrates into the skin in real time. RESULTS: Our results showed that the TXA absorption into the skin via TXVector was 2.1-fold and 3.8-fold higher compared to free TXA 3% and TXA 1% formulations, respectively. Most importantly, upon application of TXVector, the TXA penetration flux into the skin was 107% and 280% higher than that of the free TXA 3% and TXA 1% formulations, respectively. CONCLUSIONS: In summary, this study shows that the esterification-based TXVector formulation enhances the penetration flux of TXA and increases its bioavailability in the skin.