An asymmetric 1,6‐conjugate addition of thioacetic acid with para‐quinone methides has been developed by using chiral phosphoric acid catalysis in the presence of water. A series of sulfur‐containing compounds were thus obtained in high yields with good to excellent enantioselectivities. Theoretical studies indicated that the water‐bridged proton transfer is a potentially favorable reaction pathway. An unprecedented O−H⋅⋅⋅π interaction between water and the aromatic nucleus of chiral phosphoric acid was discovered to contribute significantly to the stereocontrol in the catalysis. Building bridges: The title reaction was realized in the presence of water, and successfully solved the challenge of remote stereocontrol for the para‐quinone methide substrates. Theoretical studies indicated that the water‐bridged proton transfer and an unprecedented O−H⋅⋅⋅π interaction, between water and the aromatic nucleus of the chiral phosphoric acid, play important roles in the transition state.