New and complete UBV light curves and times of minimum are presented for the Algol-type eclipsing binary V477 Cygni (Sp. A3 V+F5 V, m r = 8.5, P = 2.347 days). The binary orbit of the system is highly eccentric and the system shows an apsidal motion. Using the Wilson-Devinney method, two photometric models, without (MODEL A) and with (MODEL B) third-body light contribution to the total light of the system, are obtained. Period analysis also gives some slender evidence for the unseen third-body in the system with the orbital period of about 157 years. In the MODEL A approximation the apsidal motion period is obtained to be 371 years while it is about 434 years in the MODEL B approximation. The photometric mass ratio (q ∼ 0.75) is in good agreement with the spectroscopic value given by Popper (1968). The masses we obtained are 1.80 ′ 0.10 M O . and 1.35 ′ 0.08 M O . and the radii are 1.60 ′ 0.03 R O . and 1.42 ′ 0.03 R O . for the primary and secondary components, respectively. Absolute dimensions have been compared with the models using a moderate amount of convective overshooting and mass loss given by Claret & Gimenez (1991). In the log M-log R diagram both components are located above but close to the ZAMS. It is possible to say from the log T e -log L diagram that the secondary component is just coming to the main sequence while the primary is slightly evolved from the ZAMS. The theoretical evolutionary models give an age of 6.4 x 10 8 yrs for the system.