An efficient synergistic trityl cation ([Ph3C][B(C6F5)4])/triflic anhydride (Tf2O) catalyzed alkylation of phenols with alcohols is reported. Benefiting from formation of the triflate in situ, cheap and readily available active alcohols can be used as the alkylating reagents and the reaction proceeds under mild reaction conditions, with broad substrate scope. This protocol enables the synthesis of ortho-selective phenols and 2,4,6-trisubstitued phenols containing three different alkyl groups. tert-Amyl triflate was synthesized and mechanistic studies support a triflate-mediated alkylation process.