Immunoevasins are key proteins employed by viruses to subvert host immune responses. Determining their high-resolution structures is key to understanding virus-host interactions towards the design of vaccines and other antiviral therapies. Mouse cytomegalovirus (MCMV) encodes a unique set of immunoevasins, the m02-m06 family, that modulates major histocompatibility complex class I (MHC-I) antigen presentation to CD8+ T cells and natural killer (NK) cells. Notwithstanding the large number of genetic and functional studies, the structural biology of immunoevasins remains incompletely understood, due largely to crystallization bottlenecks. Here we implement a new technology employing sparse NMR data and integrative Rosetta modeling to determine the structure of the m04/gp34 immunoevasin extracellular domain. The structure reveals a new β fold that is representative of the m02-m06 family of viral proteins, several of which are known to bind MHC-I molecules and interfere with antigen presentation, suggesting its role as a diversified immune regulation module.