Mary Quant, who named the skirt after her favourite make of car, said she "couldn't have imagined" in 1964 that it would become a staple of women's clothing, but added: "It seemed then to be obvious, and so right.
"I had myself in mind when I designed it. "I liked my skirts short because I wanted to run and catch the bus to get to work. It was that feeling of freedom and liberation."
Quant began experimenting with shorter hemlines in the late 1950s, culminating in the creation of the mini skirt in 1964 and one of the defining fashions of the decade.
She said: "It was the girls on (London's) King's Road who invented the mini. I was making clothes which would let you run and dance, and we would make them the length the customer wanted. "I wore them very short and the customers would say, 'shorter, shorter'."
Jenny Lister, a curator at the Victoria and Albert Museum specialising in 19th century fashion, said the mini skirt marked a turning point. "It was very symbolic of the rejection of formality and the pushing back of boundaries.
"Fashion then was very much led by older, wealthier women. It was the more mature look - tailoring and twin sets.
"But with the mini skirt you can see the switch to young women leading fashion."
She added: "Young people who couldn't afford Mary Quant were rolling over the bands of their skirts to make them shorter. "There was an element of rebellion about it."
Quant, 80, who lives in Surrey, said she still most liked to see the skirt worn "short and leggy", and revealed the names of those she thought had worn it best over the years.
"Jean Shrimpton, of course, was unbeatable, and also Audrey Hepburn. Both of those were hard to beat. But there were many others... Twiggy, Sandra Paul (now Sandra Howard, the former model and the wife of former Conservative Party leader Michael Howard), Grace Coddington (US Vogue creative director)."
And asked if she thought women were ever too old to wear a mini skirt, she said: "No, it depends on your legs. Nothing more, nothing less."