"Mahela has done a decent job since taking over from Marvan Atapattu and he will continue till the World Cup," De Mel said on Monday.
"We've been working towards the World Cup and we want to make sure that Mahela feels comfortable ahead of the tournament which is not too far away."
De Mel said the decision to reappoint Jayawardene was made before he was named the Captain of the Year at the International Cricket Council's awards ceremony in Mumbai last week.
Jayawardene, 29, beat other high-profile nominees like Ricky Ponting of Australia and Rahul Dravid of India for the prestigious award.
The selectors persisted with Jayawardene despite Sri Lanka's failure to make the semi-finals of the Champions Trophy in India, although the team had been one of the favourites.
World champions Australia won the tournament in Mumbai on Sunday, defeating the West Indies by eight wickets in the final.
The Sri Lankan media reported that Jayawardene's authoritarian leadership during the Champions Trophy was not liked by the senior players. It was alleged that Jayawardene failed to consult senior players when making crucial decisions.
Jayawardene denied the allegations at a post-tournament media briefing in Colombo.
He had been accused of the same fault during Sri Lanka's tour of England in May when he declined to play veteran Sanath Jayasuriya in the second Test at Edgbaston despite the senior players wanting him in the side.
Jayawardene was made stand-in captain in March when Atapattu suffered a back injury during the home series against Pakistan and subsequently captained Sri Lanka in England and at home against South Africa.
Jayawardene has averaged 62 with the bat in Test cricket since taking over as captain even though his career average is 46.38.
In one-dayers, Jayawardene's average as captain is 46 against a career average of 32.47.
He also hit Test cricket's fourth highest individual score of 374 in July against South Africa while leading Sri Lanka to a 2-0 sweep.