U.S. uniformed service members deployed overseas face unique challenges in exercising their right to vote, often showing lower voter confidence due to difficulties in updating registration, requesting absentee ballots, and meeting tight voting deadlines. The current research evaluated the usability and trustworthiness of “CACvote,” an absentee voting system designed to enhance voting access and security for military personnel. CACvote allows voters to instantly request ballots and verify the legitimacy of their mail-in votes using secure authentication. Through a series of three experiments, the research sought to determine whether military voters find CACvote intuitive and trustworthy. First, a baseline experiment was conducted to establish usability and trust metrics with eligible military voters for a traditional electronic voting system (“Baseline”), simulating the core functions of electronic ballot-marking. Building on this model and insights from the experiment, a second formative experiment explored how additional features of the user interface—including support for authentication, ballot verification, and secure mailing processes—impact usability and trust. These findings informed subsequent system iterations. Finally, the third experiment evaluated the refined voting system’s overall usability and trustworthiness with military voters. CACvote demonstrated increased vote-casting rates and reduced assistance requests compared to the Baseline system, while maintaining similarly high levels of user satisfaction and trustworthiness. No significant differences were found in perceived workload or satisfaction between the two systems, suggesting that CACvote’s novel features integrate effectively with traditional electronic voting methods. This research also explored the relationship between trust and voting system usability, highlighting the distinct roles of past voting experience and perceived workload in shaping the voter’s trust in the voting system. These findings contribute to the exploration of how voting system usability influences voter confidence, highlighting the role of trust as a key indicator of usable security.