He said: "The wedding was fantastic. It was incredible, beautiful, went off without a hitch. Hilaria was gorgeous, Alec was over the moon. I can't be more happy for him, he looks great and he's in love and I wish him all the best."
Stephen also believes his brother's new slim physique may be down to the fact his wife is a yoga teacher.
He joked to 'Access Hollywood': "His new wife is a yoga instructor, so obviously you're seeing Alec look so well as a result of the downward dog, so to speak."
Meanwhile, Hilaria's wedding dress designer Amsale Aberra has confirmed she was "very easy going" during the creation of the gown.
She told People.com: "She is really down-to-earth and having that simplicity was important to her. It's not about saying, 'Make me something nobody has seen! Make me an outrageous dress!' She is a very easy-going person, and it did fit her personality."