Oliver Dowden has retained Hertsmere for the Conservatives, winning 29,696 votes, 18,461 more than Labour candidate Richard Butler.
This represents a small increase of 855 votes in the Conservatives' majority in the safe Tory seat.
David Cameron’s former deputy chief of staff replaces the retiring James Clappison, who served as MP for the Hertfordshire constituency for 23 years with consistent five-figure majorities.
As one of Mr Cameron's leading advisers, Mr Dowden helped to develop policy, organised briefings and monitored domestic issues. He will now enter parliament for the first time.