Testifying for the first time since his trial began more than two years ago, he told a packed courtroom he had only wanted to bring peace to Liberia's West African neighbour.
Mr Taylor, whose testimony is expected to last several weeks, continued: "I am a father of 14 children, grandchildren, with love for humanity, have fought all my life to do what I thought was right in the interests of justice and fair play."
Wearing a dark suit and tinted spectacles, he told his lawyer, Courtenay Griffiths, that the charges were "false" and "malicious".
Mr Taylor denied providing military assistance to the rebels - who were notorious for using machetes to hack the limbs off civilians - or having plotted to invade Sierra Leone with RUF leader Foday Sankoh.
He also denied having been given coffee jars full of blood diamonds by the RUF.
"Never, ever, did I receive whether it is mayonnaise or coffee or whatever jar, never received any diamonds from the RUF. It's a lie, it's a diabolical lie. Never," he said.
1989 Launches rebellion in Liberia
1991 RUF rebellion starts in Sierra Leone
1995 Peace deal signed
1997 Elected president
1999 Liberia's Lurd rebels start insurrection to oust Taylor
June 2003 Arrest warrant issued
August 2003 Steps down, goes into exile in Nigeria
Mr Taylor's legal team began setting out its case on Monday. He is the first of 249 witnesses the defence has said it may call to the stand.
His lawyers say Mr Taylor could not have micro-managed a rebel operation in Sierra Leone while also running affairs of state in Liberia.
The prosecution called 91 witnesses, many of whom provided graphic testimony of amputations, murder of children and cannibalism, before wrapping up its case in February.
Mr Taylor started a civil war in Liberia 1989, before being elected president there in 1997. He was himself overthrown by a rebellion and went into exile in 2003.
After a spell in Nigeria, he was eventually extradited from Liberia in 2006.
The trial at the UN-backed Special Court for Sierra Leone was moved to the Netherlands from Sierra Leone's capital, Freetown, amid fears it could create instability in the country and neighbouring Liberia.
A verdict in the case is expected some time next year.
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