Joining a technical standards alliance is becoming increasingly crucial for latecomer enterprises’ innovation catch-up in today's fast-paced technological environment. This study investigates the influence of latecomers’ ambidextrous innovation on technical standards alliances while highlighting the importance of alliance routines. A structural equation model is used to analyse a sample of 118 latecomer members and 45 technical standards alliances in China's strategic emerging industries. Several novel findings are reported. First, latecomers’ two types of innovation catch-up and the three dimensions of alliance routines promote alliance performance, all of which positively impact alliance performance. Second, alliance routines have different effects on latecomers’ Ambidextrous innovation catch-up. All three dimensions of the alliance routine promote utilisation innovation catch-up, whereas behavioural logic and interactive consensus hinder exploration innovation catch-up. Third, utilisation innovation completely mediates between alliance practice and performance, whereas exploration innovation only plays a partial mediating role. This study presents specific recommendations for latecomer enterprises and technical standards alliances.