We establish a unilateral global bifurcation result from interval for a class of fourth‐order problems with nondifferentiable nonlinearity. By applying the above result, we firstly establish the spectrum for a class of half‐linear fourth‐order eigenvalue problems. Moreover, we also investigate the existence of nodal solutions for the following half‐linear fourth‐order problems: x″″ = αx+ + βx− + ra(t)f(x), 0 < t < 1, x(0) = x(1) = x″(0) = x″(1) = 0, where r ≠ 0 is a parameter, a ∈ C([0,1], (0, ∞)), x+ = max⁡{x, 0}, x− = −min⁡{x, 0}, α, β ∈ C[0,1], and , sf(s) > 0, for s ≠ 0. We give the intervals for the parameter r which ensure the existence of nodal solutions for the above fourth‐order half‐linear problems if f0 ∈ [0, ∞) or f∞ ∈ [0, ∞], where f0 = lim|s|→0f(s)/s and f∞ = lim|s|→+∞f(s)/s. We use the unilateral global bifurcation techniques and the approximation of connected components to prove our main results.