The 18-year-old canoe slalomist capsized in her first run in Monday's qualification runs for the women's kayak single event but she recovered in superb fashion to reach the final where at one stage an unlikely gold medal looked on the cards.
Fox, the daughter of former multiple world champion and British Olympian Richard Fox and Myriam Fox (formerly Jerusalmi) who was a bronze medallist in kayak at the Atlanta Games in 1996, led for most of the final before France's Emilie Fer went quicker.
Despite it not being the most sought-after colour, Fox could not take her eyes off her medal.
"It's the most beautiful thing I've ever seen," she told reporters after being hugged by her parents and cheered by many fans wearing the Aussie flags and shirts.
"My goal was to make the final so at the start I was like, just give it everything.
"I put down quite a good run but there were a couple of mistakes, but all in all it was a fast time. Then there was just the wait at the finish, I was so nervous."
"No matter what the result to perform like that at an Olympic final is something I was proud of."
There was a familiar face among the starters in the form of Czech 44-year-old Stepanka Hilgertova, the gold medallist from Atlanta when Fox's French mother made the podium.
This time the Fox family got the better of Hilgertova, who first came into contact with Jessica as a baby.
"My mum won bronze in Atlanta and now here I am winning silver, it's an amazing thing to share," she said.
"Stepanka congratulated me and said 'Well done - it was a great race'. She is in her sixth Olympic Games, which is an amazing achievement."
Fox, who was born in Marseilles but moved to the canoeing heartland of Penrith in New South Wales in 1998 when her father became coach of the Australian team, said she and her mother now had bragging rights over dad.
"Someone said to my father the other day that at this rate he might be the only person in the family with no Olympic medal," she said.
"My sister is still to come, so we'll have to see."