The rapid digitalization of society has heightened calls to integrate Computational Thinking (CT) into school mathematics. However, in Ibero-America, ongoing infrastructure issues, fragmented curricula, and limited open resources impede systematic implementation. This study explores those barriers through a two-stage approach. First, a systematic review of 40 peer-reviewed empirical studies (2015–2024) examines how nine Ibero-American countries have integrated CT into primary and secondary mathematics. Descriptive trends show the prevalence of short-term pilots, heavy reliance on block-based coding and robotics (20 studies), limited use of unplugged or openly licensed materials, and only three sustained interventions focused on explicit algorithmic reasoning. Second, grounded theory analysis identified five design principles: progressive sequencing of CT across grades, foundational CT literacy before coding, dual-modality pedagogy pairing unplugged and digital tasks, explicit algorithmic reasoning routines with formative rubrics, and open resource scalability via Creative Commons licensing. Each principle is illustrated by a curated set of ten adaptable open educational resources (OER) released under CC BY-SA 4.0. The discussion places the framework within international CT research, highlights implications for teacher preparation and policy, and suggests a regional agenda for longitudinal impact studies and collaborative OER updates. By combining systematic evidence with practice-oriented design, the article provides a repeatable pathway for promoting equitable, sustained CT mathematics integration in low and mixed-infrastructure settings.