Police said Brian Matthews, 63, of London Road in Bexhill, sexually assaulted his victim over several years.
Matthews also subjected his victim to emotional and psychological abuse in a bid to normalise his behaviour and control her actions, police added.
Police said he was charged with four counts of assault on a girl under 13 by touching, four counts of assault on a female over 13 with penetration, rape of a girl aged over 13, two counts of rape of a female aged 16 or over, two counts of engaging in sexual activity in the presence of a child, three counts of sexual assault on a female, cruelty to a person under 16, and engaging in coercive and controlling behaviour.
Police said Matthews denied all charges but was found guilty by a jury on all counts except one charge of rape of a female aged over 16, and the judge discharged the jury from reaching a verdict on the charge of engaging in coercive and controlling behaviour.
At Lewes Crown Court on April 28, Police said Matthews was sentenced to 19 years in jail, including one year on extended licence.
He was also placed on the sex offenders’ register for life and given a Sexual Harm Prevention Order forbidding any contact with the victim or any child under 18 without consent of a parent/guardian and social services, or if inadvertent and not reasonably avoidable.
Police said he is also prohibited from possessing any device capable of storing or accessing digital images, unless access is provided for inspection by a police officer or police employee.
Detective Liz Brunt said: “Brian Matthews’ depraved, horrific abuse robbed his young victim of her childhood and she will have to live with the effects for the rest of her life.
“I would like to thank her for the incredible bravery she has shown not only in reporting these crimes initially, but in supporting our investigation and helping to put a dangerous predator behind bars.
“Without her courage and determination, this simply would not have been possible.”