The 27-year-old missed her penalty in the semi-final win over Italy, although she was able to score the rebound to send England to the final.
Kelly stepped up once again as the game against Spain went to penalties, but this time powered it past Catalina Coll to secure a second consecutive title for England.
Speaking to the BBC after the game, she confidently joked that she knew she was going to score from the spot this time.
Kelly said: "I am so proud of this team. So grateful to wear this badge. So proud to be English. I was cool, I was composed. I knew I was going to hit the back of the net. I don't miss penalties twice. Unbelievable.
“All the staff behind us and Sarina Wiegman - she has done it again! Unbelievable. It is going to be crazy. I hope the whole of England comes out to support us and shows their love to these girls as they deserve it."