James will be returning to more competition, on home turf at Newport
Rebecca James won two world titles plus a silver medal at the Junior World Track Championships in Moscow, Russia.
James, 17, from Abergavenny, started with silver in the 500 metre Time Trial, her 35.784 seconds beaten by Tianshi Zhong of China's 35.561.
In Sprint qualifying James broke the world record with 11.093, downing Zhong in the semi-finals before beating home favourite Ekaterina Gridenko for gold.
James again held off the Russian in the Keirin on Saturday for her second gold.
"It feels good, really good to be world champion! It's surreal and it hasn't sunk in yet," James told British Cycling.
"I have worked so hard for it and I was so happy when I got it. I couldn't stop smiling on the podium I was so chuffed and I was thinking to myself, I can't believe it.
"Now I have the world title and the world record, all the pressure on my shoulders has gone, it's great."
James will now return to Britain and go straight into more competition on home turf at the Wales National Velodrome in Newport, where the National Junior and Youth Track Championships are taking place this week.