Block shear is a common failure mode for bolted-steel shear connections. However, limited research has been conducted on the block shear failure of bolted high-strength steel (HSS) angle members. In this study, a test programme was conducted using eight single-line bolted angle specimens made of grade S690 steel and five S275 counterparts, to examine their block shear behaviour. The test parameters included steel grades, bolt arrangements (bolt number, pitch, and edge distance), and connection legs. Eleven of the specimens failed by block shear, and the remaining two by shear-out. Finite element models were developed to study the behaviour of the test specimens and to investigate the effects of connection legs on the block shear resistance. Laboratory tests and numerical analyses indicated that the block shear resistance increased only slightly with increasing lengths of the angle legs, and the relatively lower ductility of HSS did not significantly influence the block shear resistance of the HSS angles. It was also found that the predictions made by AISC 360–16 and Eurocode 3 were conservative, whereas CSA S16–14 provided unconservative predictions. The predictions obtained from design equations proposed in previous studies were also evaluated for their accuracy.