In this paper, we extend some significant Ky Fan type inequalities in a large setting to operators on Hilbert spaces and derive their equality conditions. Among other things, we prove that if f : [0, ∞) → [0, ∞) is an operator monotone function with f (1) = 1, f ′ (1) = µ, and associated mean σ, then for all operators A and B on a complex Hilbert space H such that 0 < A, B ≤ 1 2 I, we havewhere I is the identity operator on H , A ′ := I − A, B ′ := I − B, and ∇ µ is the µ-weighted arithmetic mean.