The first-ever reported Gbps backscatter transmission is presented at millimeter-wave frequencies, extremely expanding the potential of backscatter radio as a low-energy, low-complexity communication platform. Minimal front-ends are implemented that can be used for multi-gigabit communication and RF sensing, achieving scattering frequencies of at least 4 GHz away from a carrier center frequency of 24 GHz. The significantly wideband operation of these minimal communicators will enable broadband wireless transmission with less than 0.15 pJ/bit front-end energy consumption at 4 Gbps and sensing with an extensive number of low-power sensors. The front-ends are additively manufactured using inkjet printing on flexible substrates that can be directly integrated with wearables for challenging mobile applications in 5G and the Internet of Things (IoT).