The Pussycat Dolls singer was photographed wearing a ring on her engagement finger as she and Hamilton left a hotel in Sao Paulo, Brazil, early this week.
Scherzinger joined the Formula One star's family as they watched him race to victory in the Brazilian Grand Prix at the weekend. Adding a video to YouTube, she later said: "I'm so excited, I feel like I'm on top of the world right now.
"Why? Because I want to congratulate my boyfriend Lewis Hamilton for being the official Formula One World Champion."
She added: "Congratulations baby, I love you, I love you, I love you. It's all about the love and it's just good times."
The couple are reported to have begun dating in May.
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