The 19-year-old from Blackburn, a former ballet dancer, threw a UK junior record of 66.01 metres to beat Slovenia's Barbara Spiler by 73 centimetres.
"I’m exhausted but so excited," she said.
"I got a bit tired between the middle two rounds but I knew I just had to go for it on my last throw.
"I thought after qualifying that I had a really good chance but I wanted to stay calm and just focus on the day because anything can happen in a final.
"My grandparents are here watching and they’re a great help to me and my mum and dad will be back home excited jumping up and down.
"The weather didn’t really help me because I’m not used to it being so hot.
"The fact that I was neck and neck with the Slovenian all the way through made it a really good competition and really drove me forward."
Hitchon, who only took up the sport in 2007 having previously played netball, had finished third in the European Junior Championships last year.
She joins Jodie Williams, the winner of the 100m earlier in the Championships, on Britain's roll of honour at these Championships.
"I don’t think it’s going to sink in all," Hitchon said.
"The key is to save energy when you’re out here for a long time – two weeks is a long time to wait through holding camp and into competition and people can get really uptight.
"If you stay calm it really helps."
July 2010: Stormy end to Williams' 151 unbeaten race streak
July 2010: Williams claims world junior victory and extends unbeaten record to 149 races