The pair took victory in the girls’ synchronised platform final in Russia with an impressive performance.
The new pair scored 278.46 points to finish more than 20 points ahead of home favourites Alina Arefeva and Polina Saekova, who came second.
After a solid start, Martin and Spendolini-Sirieix moved well clear at the top of the standings with their third dive – a back two-and-a-half somersaults and one-and-a-half twists in a pike position.
They went even better with their fourth dive, picking up another 67.50 points with a forward three-and-a-half-somersaults in a pike position.
The British duo went into the final round knowing they just needed 30 points to win and they comfortably achieved that by scoring 50.88 points for their inward three-and-a-half somersaults in the tuck position.
Earlier in the day, Martin had finished fifth in the girls’ A individual final. She was just seven points away from winning a medal.
Fellow Plymouth diver Euan McCabe will be in action on Thursday in the boys’ B platform event. Team-mate Aidan Heslop will compete in the three-metre synchro on Saturday and the boys’ A platform event on Sunday.
Meanwhile, a host of Plymouth’s younger divers will be in action at the Swim England Diving National Age Group Championships in Sheffield, which start on Thursday and run through to Sunday.