The VEGF family of pro-angiogenic factors has represented a pillar for targeted cancer therapy for more than a decade. In comparison, the field of protein homeostasis (proteostasis) focusing on the Unfolded Protein Response (UPR), an endoplasmic reticulum (ER) stress-induced signaling cascade, has just recently emerged as an attractive anti-cancer approach. Recent findings suggest that both signaling pathways are incontestably interrelated to ensure cell survival. Herein, we summarize recent findings that demonstrate how these two fundamental aspects of cancer cell survival intersect and provide genetic and pharmacological evidence of the interplay between angiogenic factors such as VEGF-A or PlGF and the individual members of the UPR such as IRE1, PERK and ATF6. We further describe how this interaction does not only affect the cancer cells, but also the surrounding microenvironmental niche that is also involved in tumor progression. Furthermore, by summarizing the recent therapeutic implications of both anti-angiogenic and proteostatic approaches, we emphasize how these novel findings could be used synergistically to improve cancer therapy.