In April 1660, Knatchbull was elected Member of Parliament for New Romney together with his father until the following year. In 1685 he succeeded his father as baronet and was elected MP for Kent.
In April 1660, Knatchbull became a Member of Parliament (MP) for New Romney along with his father; they both served until the following year. In 1685, he inherited his father's baronetcy and was re-elected as an MP for Kent.