A catalyst composition for selectively hydrogenating a conjugated diene polymer in a homogeneous system is provided, wherein the conjugated diene polymer comprises a conjugated diene monomer or a combination of a conjugated diene monomer and a vinyl aromatic monomer. The catalyst composition includes the catalyst components of (a) a titanium compound; (b) an organometallic compound; and (c) an oligomer containing a polyglycol segment. The hydrogenated polymer produced using the catalyst composition and the method thereof is also provided.