A novel multiplier-based approach for robust controller design with real parametric time-varying uncertainty is proposed. Sufficient conditions for robustness analysis are derived in terms of noncausal dynamic multipliers that depend on the the rate of uncertainty variation. An affine parametrization of such stability multipliers is introduced and the search for suitable multipliers is reduced to a convex minimization formulated as a linear matrix inequalities (LMI) problem. Stable dynamic scalings derived from this multiplier are employed to formulate an equivalent scaled H-infinity norm condition for robust stability, based on which a mu/k(m)-synthesis procedure is proposed to design robust controllers for the time-varying parametric uncertainty considered.