Mark Smith, 41, admitted 29 counts of abuse dating back to the 1980s at an earlier hearing at Norwich Crown Court, Norfolk Police said.
These included rape, indecent assault, indecency with a child, sexual assault and possession of an indecent image of a child.
Smith, of Philadelphia Lane, Norwich, was sentenced to life imprisonment at Norwich Crown Court on Friday and was ordered to serve a minimum of 16 years.
He was also placed on the Sex Offenders Register for life.
The offences took place in North Yorkshire and Norwich between 1985 and 2015 and involved six victims, all under the age of 14.
Detective Inspector Dave Freeman said: "Smith is a sexual predator and clearly poses a danger to children, a threat which is reflected in the life sentence imposed by the judge.
"This was a truly abhorrent case and I hope it provides some closure for his victims."