Sandra Major, who was with the politician when she was murdered, was awarded an MBE by the Prince of Wales for parliamentary services and services to the community in Batley and Spen.
Mother-of-two Mrs Cox was shot and stabbed as she arrived for a constituency surgery in Birstall on June 16, 2016.
She had been elected as Labour MP for the Batley and Spen constituency just 13 months earlier.
After the ceremony Mrs Major jokingly compared her former boss to a Winnie the Pooh character because of her boundless enthusiasm.
"She was really crazy," she said. "I always used to say she was like Tigger she just used to jump about - she had so much energy.
"And she was very inspirational. She was a lovely lady. It was a terrible tragedy."
Mrs Major described how for many years she has worked in the community from starting a playgroup in a deprived area to acting as a school governor and co-founding Batley foodbank.