The New York Times has a mixed review from the time of the film's release. Moria gives it 3 out of 5 stars and says, "What makes the rehashed story worthwhile is Ray Harryhausen’s stunning animation work". Stomp Tokyo says, "In our minds this film is a Ray Harryhausen film. Just about everything in the film that isn't stop-motion animated is window dressing. And unlike most special effects today, these were really the work of one man with a recognizable style." 1000 Misspent Hours calls it "an entertaining little exercise in genre-juggling."
DVD Talk says, "The Valley of Gwangi delivers the best of several worlds." Rotten Tomatoes has a critics score of 75%.