Christopher Greenfield was born c1653, the second son of Thomas Greenfield of Witton, Blackburn. He married Sarah, the stepdaughter of Seth Bushell, the vicar of Preston, in 1678, shortly after he was called to the bar. 
Greenfield appears to have established himself in Preston before his marriage. A court leet record suggests he was living in Church Street near Cockerhole (the present Manchester Road) in 1674.  At his marriage or very soon after he moved to Friargate.  There he occupied a four-storey property, one of the largest in the town.  His elder brother Thomas also had a house in the town.
He pursued an active career as a lawyer, keeping chambers at Gray’s Inn in London. He was elected MP for Preston in 1690. Soon after his election he was involved in gathering evidence against Lancashire Catholics allegedly involved in a Jacobite plot. November 1692 found him representing the bishop of Chester in court, seeking to prevent Dissenters registering an Anglican chapel in Wigan as a meeting house. And the next month he was speaking against the Quakers’ affirmation bill in the Commons. He was knighted at the beginning of 1693
In October 1694 he represented one of the accused at the Manchester Jacobite trial of Lancashire Catholics (see Sir Thomas Clifton article for more on the trial).
He lost his seat in the 1695 election and failed in his attempt to regain it in 1698. He did not contest the seat again before his death in 1706, although he remained involved in local politics.