This study analyzes the end-to-end (e2e) outage probability (OP) performance of a multi-hop relay schemes based on non-orthogonal multiple access (NOMA) in underlay cognitive radio networks. In the proposed model, a secondary source transmits two distinct data to its two secondary destinations. In particular, the secondary source uses NOMA to send two encoded packets simultaneously to two destinations, with the help of intermediate secondary decode-and-forward (DF) relays. To successfully recover the original data, each destination must gather sufficiently encoded packets. Moreover, all the secondary transmitters—including the source and intermediate relay nodes—must adjust their transmitting power to avoid causing harmful interference to a primary user. This paper derives probability that an encoded packet fails to reach its intended destination, which is then used to calculate the e2e OP for each destination. Finally, Monte Carlo simulations are used to check the accuracy of the derived expressions.