The availability of pure individual betalains in sufficient quantities which permit deeper understanding is still a challenge. This study investigates the high-yielding semisynthesis of betaxanthins using betalamic acid from a natural source (Opuntia dillenii), followed by condensation with ʟ−amino acids and further purification. Moreover, the color stability of the four synthesized individual betaxanthins, namely proline (ʟ−ProBX), alanine (ʟ−AlaBX), leucine (ʟ−LeuBX), and phenylalanine (ʟ−PheBX) betaxanthins, was investigated at different pHs. Their relative contribution to free radical scavenging was also scrutinized by TEAC and DPPH. ʟ−AlaBX and ʟ−LeuBx showed a significantly (p Opuntia dillenii for the first time, and to establish their color properties and antioxidant capacity. This study could be a step forward in the development of the best natural food colorant formulation, based on the betalain structure, which is of special interest in food technology.