The incorporation of non-canonical amino acids into proteins has emerged as a promising strategy to manipulate and study protein structure-function relationships with superior precision in vitro and in vivo. To date, fluorescent non-canonical amino acids (f-ncAA) have been successfully incorporated in proteins expressed in bacterial systems, Xenopus oocytes, and HEK-293T cells. Here, we describe the rational generation of a novel orthogonal aminoacyl-tRNA synthetase based on the E. coli tyrosine synthetase that is capable of encoding the f-ncAA tyr coumarin in HEK-293T cells.