New rules mean the people making TV adverts can no longer put them out at the times when you're tuning in.
The ban will cover any food that is high in fat, salt and sugar - so that could include fast food, fizzy drinks, sweets and some snacks.
There will be a total ban on ads on children's channels, as well as during kids' shows and adult programmes watched by lots of young people.
The changes, starting in January, aim to stop kids getting overweight.
An organisation called Ofcom - which looks after what's put on TV - says the ban will mean kids will see less adverts for unhealthy food.
TV ad ban details
All kids' programmes
All kids' TV channels
Programmes aimed at kids, like music shows
Entertainment shows which lots of kids might watch
Food officials will decide which foods are too high in fat, sugar and salt to be advertised to children.
The ban will be brought in over two years to allow for the fact that companies have already started working on adverts.
But some health experts think the ban does not go far enough and more should be done.
The ban doesn't apply to the web or the internet so you could still be seeing junk food ads there.