From April 2004 to March 2005, Kato was a regular guest student on Italian Conversation, a 25-minute NHK TV program for beginners of Italian.
She subsequently began appearing in commercials and became a popular model after appearing in Zexy, a Japanese bridal magazine, in 2004. She appeared in the Japanese film Tokyo Tower with Jun Matsumoto in 2005. In late 2005, she began appearing in Japanese television dramas such as Kindaichi Shonen no Jikenbo. She later won the "Best Newcomer Award" for her performance in Dance Drill (also known as Dandori in Japan) in 2006.
On 22 June 2011, Kato's 26th birthday, she married Japanese football player Daisuke Matsui. The next day, she announced on her blog her four-month pregnancy with their first child. She gave birth to a son on 14 December 2011 at 6:30 AM in France.