Synthetic biology incorporates modification, simulation, regeneration, or synthesis of biological environments using synthetic techniques for clinical or biomanufacturing purposes. Some of the tools employed for the purpose include clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9, transcription activator-like effector nucleases, gene circuits, computational models, and induced pluripotent stem cells. Synthetic biology is an emerging approach for drug repurposing, the process of finding new therapeutic uses for approved drugs to save the cost and time for drug discovery, reducing the time period from inception to approval. With the help of synthetic biology, genetically modified organisms and cells can be generated that can be employed for drug screening purposes. Using such techniques opens up a new means for drug development for otherwise incurable diseases such as cancer, neurodegenerative diseases, antimicrobial resistance, and rare diseases. This chapter highlights the use of synthetic biology for revolutionizing drug repurposing that can pave the way for precision medicine and personalized therapeutics.