Rosmarinic acid (RA) is an important naturally occurring polyphenol from plants of the mint family with many health-promoting benefits, but these can be influenced by its poor bioavailability. In this study, the bioavailability and bioefficacy of RA as RA-phospholipid complex (RA-PLC) and as RA-PLC oil solution (RA-PLC-ME) were evaluated. Evaluations in Caco-2 cell monolayers in vitro revealed that the membrane permeability of RA-PLC and RA-PLC-ME was significantly increased (p < 0.05) over that of unformulated RA. Pharmacokinetic studies additionally revealed that RA-PLC and RA-PLC-ME were 1.2- and 2.9-fold more bioavailable than unformulated RA, respectively. Evaluation of bioefficacy in vivo demonstrated that oral administration of RA-PLC-ME produced a greater reduction in the serum levels of AST and ALT (p < 0.05, p < 0.01), and markedly increased antioxidative properties (p < 0.05), compared with unformulated RA. This study indicated that PLC-ME could act as an effective delivery device for RA to enhance oral bioavailability and bioefficacy.