Senna was born in São Paulo, a city in Brazil. When he was four years old, he first got into a kart. When he was 13, he entered a karting competition for the first time. A fun fact is that he started his first kart race on pole position. The start places were written on pieces of paper and put in a driver's helmet, and he drew number one. Because he was a lot lighter than the other racers, he was much faster than all of them. He won the "South American Kart Championships" in 1977 and was runner-up in the World Championship, but he never won it.