Allylphenol is an important and ubiquitous structural motif in biologically active natural products and pharmaceuticals. Herein, we report a Rh₂(esp)₂-catalyzed reaction of diazoquinones with allylboronates, which provides access to a range of allylphenols, including para-allylphenols, ortho-allylphenols and allylnaphthols, in 44–94% yields and under mild conditions. The synthetic utility of the method was demonstrated by the short synthesis of two bioactive molecules. The mechanistic studies suggest that the reaction proceeds through a cyclopropanation/ring opening/aromatization pathway.