Osasuna B was founded in 1962 as Osasuna Promesas, being renamed in 1991. It first reached the third division in the 1982–83 season, then again in 1987, the latter spell eventually lasting more than two decades.
A change in the club structure from 2016 means that an affiliate club, CD Iruña of the Tercera División will be part of the Osasuna structure.[2] The Iruña team must play at least one division below Osasuna B.
In the 2018-19 season the club won the Group 15 of the Tercera División.[3] After the win over Cádiz B in the promotional play-offs, Osasuna B promoted to Segunda División B for the 2019-20 season.[4]