Hosts Sri Lanka lost to West Indies by 36 runs for their fourth successive defeat in World Cup finals in front of a full house at the R. Premadasa Stadium.
"It's not a surprise... I have had a chat with the selectors before the tournament started. I was going to step down from T20 captaincy after this World Cup," Jayawardene told reporters.
"I personally feel that for Sri Lanka going forward, we need a younger leader. I think it's a great opportunity for somebody to start in the T20 format.
"So I have spoken to the selectors. They were quite happy with the choice I have made."
Jayawardene, who played in each of the team's two 50-over World Cup final losses in 2007 and 2011 and the T20 final loss to Pakistan in 2009, said he would continue to lead the team in the other two formats.
"I haven't stepped down from other formats. I took over (to lead) till the Australian tour (in December)," he said.
"I will assess what I want to do after that. But this I am going to step down, they will make a call on who is going to lead the national team in T20."
Jayawardene said Sri Lanka would have to figure out how to break the World Cup final jinx.
"It hurts a lot, because you want to do something special, not just personally, but for the public as well," the stylish right-handed batsman said.
"We've been playing really good cricket but we haven't been able to cross that hurdle. So it hurts as a player, as a cricketer, as an individual...
"But we just need to move on, try, and see how well we can get over this and get back on and keep fighting again."
It was a rare off-day for Lasith Malinga, considered one of the best bowlers in the shortest format with his unique slinging action and toe-crushing yorkers.
Marlon Samuels hit five sixes off Malinga to wrest back the momentum as the unorthodox paceman gave away 54 runs off his four overs.
"He (Malinga) went to areas where he is very comfortable with when somebody is going after him. That's why I brought him because they were going big and I backed my number one bowler to deliver.
"But Marlon batted really well, so hats off to him. He played some really good shots. So that's one of those days when the momentum shifted and it was pretty tough to get back in it again."
- Sri Lanka