This study empirically examined the promotion and implementation of open science measures among high‐performing journals of Brazil, Mexico, Portugal, and Spain. Journal policy related to data sharing, materials sharing, preregistration, open peer review, and consideration of preprints and replication studies was gathered from the websites of the journals. Four hundred articles were coded for the inclusion of data availability statements, conflict of interest disclosures, funding disclosures, DOI, ORCID, and continuous publishing. Analyses found a higher promotion of open science measures among Brazilian journals than their Portuguese counterparts, and higher promotion of open science measures among international journals than their domestic counterparts. Analyses found higher implementation of open science measures among Brazilian journals than their Portuguese and Mexican counterparts. One journal out of 40 encouraged preregistration of studies; none encouraged replication studies and none had implemented open peer review. These findings reveal reasonably strong implementation of secondary open science measures (e.g., DOI, ORCID, conflict of interest and funding source disclosure) among the sample, but weaker implementation of primary measures (e.g., open data, open materials, replication studies and open peer review). The implications of these findings are considered and suggestions are made to bolster the adoption of open science measures among Ibero‐American scientific journals.