Gold(I)-catalyzed stereoselective β-glycosylation of primary alcohols is achieved using the orthogonally protected mannosyl α- ortho -hexynylbenzoate (OABz) donors devoid of 4,6- O -tethering groups used in conventionally constructing β-mannosidic bonds. The potential of this methodology is showcased by the first assembly of β-1,6-tri/hexa-/nonamannosides and related sulfated congeners through a convergent strategy. The synthesis features the stereocontrolled β-glycosylation of α-trimannosyl OABz donors and the late-stage sulfonation. This work is expected to expedite the preparation of β-1,6-mannans and functionalized derivatives.