The royal mother-of-two, 33, wore a Sportmax wool coat and a Cezanne Paintbox Pleated Dress from Great Plains, People reports.
The royal donned the same dress in March 2013, in Grimsby, England, at the National Fishing Heritage Centre.
Duchess Kate walked to the church next to her husband Prince William in Aquatalia Rhumba boots.
Kate also wore the high-heeled boots in 2012, when the pregnancy rumors started circulating, as she helped to officially open the playing field at St. Andrew’s School in Pangbourne, England.
The Duke and Duchess of Cambridge attended St. Mary Magdalene Church in Sandringham on Christmas Day.