This paper presents the results of the theoretical and finite element analyses of the lateral–torsional buckling of I-girders with corrugated webs under uniform bending. Even though lateral–torsional buckling could dominate the flexural strength of I-girders composed of thin-walled members, the torsional rigidity of the I-girder with corrugated webs is not yet sufficiently understood, for example, the method to evaluate the warping constant. In this paper, previous studies on the bending and torsional rigidities of the I-girder with corrugated webs are first discussed. Then, approximated methods for locating its shear center and calculating the warping constant are proposed. Using the proposed methods, the lateral–torsional buckling strength of I-girder with corrugated webs under uniform bending can be calculated easily. A series of finite element analyses are conducted and their results are compared with those of the proposed methods. Based on these comparisons, the proposed methods are successfully verified. Finally, the effects of the corrugation profiles of the web on the lateral–torsional buckling strength of the I-girder with corrugated webs are further discussed.