Field margins on arable land, such as seed-rich strips (SRS), are an important and widely implemented conservation measure under agri-environment schemes. They are intended to contribute to the provision of scarce food resources and shelter for various farmland species. Although SRS are primarily designed to provide critical resources for wildlife during the winter, they may also contribute to biodiversity conservation throughout the year and across the full annual cycle of farmland species. However, empirical evaluation of their conservation potential over the annual cycle and across multiple taxa is missing. Therefore, in this study, we conducted a year-round assessment of the conservation potential of SRS for several avian (farmland birds and seed-eating species in particular) and mammalian (European hares and common hamsters) farmland species in arable-dominated agricultural landscapes. Moreover, we investigated the role of the habitat context (i.e., SRS placed along farmland hedges or inside crop fields) of SRS on species abundance and diversity. Our results showed that during the entire year, SRS significantly increased farmland bird abundance and species diversity (including seed-eating species), as well as European hare and common hamster abundance, compared to the controls (i.e., conventionally managed arable land). The SRS utilization varied seasonally, with bird abundance in them being significantly higher from late summer through winter, while European hare abundance increased significantly only in the autumn and winter months. Notably, the most substantial differences in farmland bird diversity between the SRS and control areas were observed from August to November, whereas the greatest disparities in bird abundance occurred during the winter months, particularly from December to February. The habitat context of the plots (both SRS and controls) generally did not affect the abundance or species diversity of farmland birds. However, the abundance and species diversity of seed-eating birds were higher in plots located along hedges. The opposite pattern was found for the European hare. We conclude that implementing SRS could significantly help in the conservation of avian and mammalian species in arable farmlands. This is true not only in the autumn and winter, when the dense and structurally complex vegetation in SRS offers abundant nutrient-rich seeds and cover, but also in the summer, when SRS provides invertebrates for a variety of farmland species.