[1] Mackworth was returned unopposed as Member of Parliament for Rutland at a by-election on 17 December 1694 following the death of his father.
In 1704, the Company of Mine Adventurers received a Royal Charter, but by 1710 was running into financial difficulties which resulted in a parliamentary enquiry.
At the 1713 general election he was returned on behalf of the administration as MP for Portsmouth, but did not stand for Parliament in 1715.
However, he was ruined financially by the cost of this contest and his estates including Normanton Hall were sold by order of the court of Chancery to pay his debts, He did not stand at the 1727 general election.
He also left some property in trust for a supposed illegitimate son, Thomas Mackworth.