He replaces Sue Killen, who stood down in August after 10 years in the role.
Houghton-Brown said in a statement that he had worked for some of Britain’s finest charities and joining St John Ambulance was a "dream come true".
He said: "I aspire to see volunteers increasing their role in building safe and healthy communities and I cannot think of a better place to realise that vision."
A St John Ambulance spokeswoman said the charity did not wish to disclose how much Houghton-Brown would be paid. The charity’s most recently available annual report, for 2016, shows that the highest-paid individual, who is not named, was paid between £150,001 and £160,000 in that year.
The charity had an income of £102.5m in 2016, employs about 1,700 people and has more than 30,000 volunteers, according to details filed with the Charity Commission.
Houghton-Brown will take up his new role on 1 January.