The 17-year-old singer began dating the Disney starlet last year and while they refused to confirm their romance for months, Justin says he`s smitten with Selena as she makes him "really happy".
He said: "Selena is ... ah - she`s amazing. She makes me really happy."
When a TV host in Taiwan said, "She makes us all very happy. So, she`s a great woman," a grinning Justin replied: "Yeah."
As well as Justin gushing about Selena, the former `Wizards of Waverly Place` actress recently opened up about their relationship saying she was glad to have found someone who could understand the pressures of a career in the limelight.
She said: "I`m blushing! He`s been in my life for so long and it`s just nice to have someone that understands what you`re going through."
However, life hasn`t always been so easy for the pair as Selena recently admitted she was "hurt" by Justin`s fans who openly criticised her through social networking site twitter.
She explained: "It`s hard. It hurts, it really does. I don`t feel like I`m doing anything wrong. I`ve been best friends with him for a very long time. It does hurt my feelings a lot but I try not to focus on it. I have a strong family and great fans."