Leighton became deputy chairman of the company in March, a post that was intended to be a preparatory step to taking over the top spot. He will succeed chairman Lynn Wilson, who will become non-executive deputy chairman.
Managing director John Tutte will be appointed group chief executive, also with effect from 1 January.
Wilcon is one of several companies on which Leighton is active. He is a non-executive director of BSkyB, non-executive chairman of lastminute.com, non-executive chairman of Leeds Sporting and non-executive director of Dyson Appliances.
Leighton had also been a non-executive director of Wilcon for five years before becoming deputy chairman.
Wilcon builds 4500 homes a year and had a turnover of £469m in the 12 months to 31 December 1999.