Spanish lupin, Lupinus hispanicus Boiss. et Reut. is an untapped grain legume species characterized by moderate frost resistance, tolerance to poor soil and waterlogging, high yield stability, and remarkable seed protein content. It has been recognized as a good candidate for domestication to broaden the palette of crop diversity. One of the key characteristics that need to be precisely addressed during domestication is the vernalization responsiveness of flowering, which is advantageous in autumn sowing due to improved frost tolerance, whilst undesired in spring sowing as it delays flowering. Ahead of L. hispanicus breeding, in the present work, we aimed to recognize existing phenotypic variability of flowering time and vernalization response and to evaluate the genetic architecture of early and late phenology by DArT-seq genotyping and genome-wide association study (GWAS) in world germplasm collection of the species. Controlled environment phenotyping revealed high variability of flowering time and vernalization responsiveness and significant correlations with population structure. DArT-seq genotyping yielded 23 728 highly polymorphic markers distributed extensively across all 26 chromosomes. GWAS identified a number of markers significantly associated with flowering time with or without pre-sowing vernalization, including those overlapping with the two major quantitative trait loci reported previously for white lupin species. Microsynteny-based analysis of the genetic content of L. hispanicus genome regions carrying significantly associated markers highlighted several candidate genes from photoperiodic and vernalization pathways. To summarize, the present study identified germplasm resources for autumn- and spring-sown cultivation of L. hispanicus and provided tools for marker-assisted selection towards required flowering phenology.