When do angel investors invest in a diversified portfolio of industries? Drawing on angel investing and temporal research, we examine the effect of angels’ long-term orientation – their time horizon – on the industry diversification of their venture portfolios. We argue that short-term oriented angels are more willing to take on more diversified industry portfolios to seize emerging opportunities. Moreover, when diversifying into unfamiliar industries, the former will favor deals in dynamic and “hot” industries with potentially quicker returns, whereas angels with long-term orientations will opt for capital-intensive industries requiring more patient effort. Based on a longitudinal analysis of 133 angels from 2010 to 2019, our results largely support our hypotheses. Our study establishes angels’ temporal orientation as a critical antecedent of portfolio industry diversification strategy.