Background: There is a lack of treatment plurality at step 2 of Improving Access to Psychological Therapies (IAPT) services. This project therefore sought to develop and pilot a cognitive analytic informed guided self-help treatment for mild-to-moderate anxiety for delivery by Psychological Wellbeing Practitioners (PWPs). Method: Medical Research Council treatment development guidelines were used. Phase I included development of the six-session treatment manual using practice guidelines, small-scale modelling (n = 3) and indicated manual iterations. Phase II consisted of a mixed methods case series design (n = 11) to index feasibility, uptake and clinical outcomes. Results: Cognitive analytic guided self-help (CAT-SH) met established quality parameters for guided self-help. A high treatment completion rate was observed, with 10/11 patients who attended the first treatment session subsequently completing full treatment. Six out of ten patients completing full treatment met reliable recovery criteria at follow-up. Effect sizes and recovery rates equate with extant PWP outcome benchmarks. Practitioner feedback indicated that delivery of CAT-SH was feasible. Conclusion: CAT-SH shows promise as a low-intensity treatment for anxiety, and so further, larger and more controlled evaluations are indicated.