In 1988, on the 150th anniversary of the abolition of slavery in the British Empire, Knibb was posthumously awarded the Jamaican Order of Merit.

His father was a tradesman, Thomas Knibb, and his mother, Mary (née Dexter) was active in the local independent church.

Together they were following the pioneering work of the African preacher George Lisle, a former slave from Virginia who had arrived in 1782 and founded a Baptist church in Kingston.

The iron hand of oppression daily endeavours to keep the slaves in the ignorance to which it has reduced them.Knibb made his feelings clear.

When Sam Swiney, a black slave, was unjustly accused of a minor offence, Knibb spoke for him in court.

But Knibb refused to let the matter drop, and published details in an island newspaper, for which he was threatened with a prosecution for libel.

[5]: 17–23 In the mayhem George Bridges, an Anglican clergyman, formed an association of white Jamaicans to oppose the anti-slavery movement by all necessary means.

Sceptics were convinced, waverers became decided, apathetic people were roused, and great numbers of hearts everywhere kindled to irrepressible support.Knibb himself later recalled his efforts.

I was forced from the den of infamy and from a gloomy prison, with my congregation scattered, many of the members of my church murdered, and multitudes of the faithful lashed.

I came home and I shall never forget the three years of struggle, and the incessant anxiety upon my spirit as I passed through the length and breadth of the country detailing the slaves' wrongs.Knibb was summoned to appear before committees of both Houses of Parliament that had been convened to investigate the state of the West Indian colonies.

Knibb recalled that "in those seven years, through the labour of about twenty [Baptist] missionaries, 22,000 people were baptised upon their profession of faith in Jesus Christ".

Thomas Swan, who led Birmingham's Cannon Street Baptist chapel, was able to meet Knibb who he and Joseph Sturge had worked hard to support.

These two men spoke to 5,000 people at Birmingham Town Hall[8] and Beckford became the central figure in Haydon's painting that commemorated the World Anti-Slavery Convention.

[9] Knibb died of fever in Jamaica on 15 November 1845, aged 42, and was buried at his Baptist Falmouth Chapel, the service attracting eight thousand African islanders.

His funeral sermon by pastor Samuel Oughton was taken from Zechariah, xi, 2 "Howl, fir tree, for the mighty cedar is fallen".

In 1988, the 150th anniversary of the abolition of slavery in the British Empire, Knibb was posthumously awarded the Jamaican Order of Merit; the first white man to receive the country's highest civil honour.

This monument was erected by the emancipated slaves to whose enfranchisement and elevation his indefatigable exertions so largely contributed; by his fellow labourers who admired and loved him, and deeply deplore his early removal; and by friends of various creeds and parties, as an expression of their esteem for one whose praise as a man, a philanthropist, and a Christian minister, is in all the churches, and who, being dead, yet speaketh.William Knibb Memorial High School in Trelawny, Jamaica is named for him.