Aim: To examine whether designed‐to‐be‐rigid ankle–foot orthoses and footwear combinations with individualized alignment and footwear designs (AFO‐FC/IAFD) would be more effective than designed‐to‐be‐rigid AFO with non‐individualized alignment and footwear designs (AFO‐FC/NAFD) in children with cerebral palsy (CP). Method: Nineteen children with bilateral spastic CP were randomized to AFO‐FC/NAFD (n = 10) or AFO‐FC/IAFD (n = 9) groups. Fifteen were male, average age 6 years 11 months (range 4 years 2 months–9 years 11 months), classified in Gross Motor Function Classification System levels II (n = 15) and III (n = 4). The Pediatric Balance Scale (PBS), Gait Outcomes Assessment List (GOAL), Patient‐Reported Outcomes Measurement Information System (PROMIS), and Orthotic and Prosthetic Users' Survey (OPUS) measures of satisfaction were collected at baseline and after 3 months' wear. Results: Compared with the AFO‐FC/NAFD group, those with AFO‐FC/IAFD demonstrated greater change in PBS total scores (mean 12.8 [standard deviation 10.5] vs 3.5 [5.8]; p = 0.03) and GOAL total scores (3.5 [5.8] vs −0.44 [5.5]; p = 0.03). There were no significant changes in OPUS or PROMIS scores. Interpretation: After 3 months, individualized orthosis alignment and footwear designs had a greater positive effect on balance and parent‐reported mobility than a non‐individualized approach. No effect was documented for the PROMIS and OPUS. Results may inform orthotic management for ambulatory children with bilateral spastic CP. What this paper adds: Balance and parent‐reported mobility increased more over time for the ankle–foot orthoses and footwear combinations with individualized alignment and footwear designs (AFO‐FC/IAFD) group.Changes in balance over time suggest a therapeutic effect of the AFO‐FC/IAFD approach. [ABSTRACT FROM AUTHOR]