The marketing of heated tobacco products (HTPs), like IQOS, influences consumers’ perceptions. This mixed-methods study analyzed (i) survey data (2021) of 2222 US and Israeli adults comparing perceptions of 7 IQOS attributes (design, technology, colors, customization, flavors, cost and maintenance) and 10 marketing messages (e.g. ‘Go smoke-free…’) across tobacco use subgroups and (ii) qualitative interviews (n = 84) regarding IQOS perceptions. In initial bivariate analyses, those never using HTPs (86.2%) reported the least overall appeal; those currently using HTPs (7.7%) reported the greatest appeal. Notably, almost all (94.8%) currently using HTPs also currently used cigarettes (82.0%) and/or e-cigarettes (64.0%). Thus, multivariable linear regression accounted for current cigarette/e-cigarette use subgroup and HTP use separately; compared to neither cigarette/e-cigarette use (62.8%), cigarette/no e-cigarette use (17.1%) and e-cigarette/no cigarette use (6.5%), those with dual use (13.5%) indicated greater overall IQOS appeal (per composite index score); current HTP use was not associated. Qualitative data indicated varied perceptions regarding advantages (e.g. harm, addiction and complexity) of IQOS versus cigarettes and e-cigarettes, and perceived target markets included young people, those looking for cigarette alternatives and females. Given the perceived target markets and particular appeal to dual cigarette/e-cigarette use groups, IQOS marketing and population impact warrant ongoing monitoring to inform regulation.