In July 2010, Postigo signed with CA Osasuna, being initially assigned to the B side also in the third division.[2] On 13 January 2012, he appeared in his first game as a professional, playing the last 11 minutes of a 1–2 home loss against FC Barcelona in the round of 16 of the Copa del Rey.[3]
Postigo was released by the Navarrese in May 2012,[4] and shortly after moved to another reserve team, Getafe CF B. In July of the following year, however, he was released again,[5] returning to former club Leganés shortly after.[6]
On 20 July 2015, Postigo moved abroad for the first time in his career, joining Spezia Calcio from the Italian Serie B after paying his €300.000 buyout clause.[7] On 16 July of the following year, he returned to Spain, signing a two-year contract with Segunda División side Levante UD.[8]
Postigo contributed two goals in 36 appearances in his first season, as his team achieved promotion to La Liga.[9][10] He made his debut in the competition on 21 August 2017, starting the 1–0 home win over Villarreal CF.[11] His first goal came the following 11 February, but in a 3–1 defeat at Valencia CF.[12]