The seminal discovery of ribonuclease P (RNase P) and its catalytic RNA by Sidney Altman has not only revolutionized our understanding of life, but also opened new fields for scientific exploration and investigation. This review focuses on human RNase P and its use as a gene targeting tool, two topics initiated in Altman’s laboratory. We outline early works on human RNase P as a tRNA processing enzyme and comment on its expanding non-conventional functions in molecular networks of transcription, chromatin remodelling, homology-directed repair and innate immunity. The important implications and insights from these discoveries on the potential use of RNase P as a gene targeting tool are presented. This multifunctionality calls to a modified structure-function partitioning of domains in human RNase P, as well as its relative ribonucleoprotein, RNase MRP. The role of these two catalysts in innate immunity is of particular interest in molecular evolution, as this dynamic molecular network could have originated and evolved from primordial enzymes and sensors of RNA, including predecessors of these two ribonucleoproteins.