Head coach Leo Cullen pinpointed a clinical attacking edge as key to Leinster's success as they reached the Champions Cup final for the first time since 2012.
First-half tries from James Ryan, Cian Healy and Fergus McFadden were complemented by further converted scores from man-of-the-match Scott Fardy and Johnny Sexton, as the Irish province - unbeaten in eight European fixtures this season - beat Scarlets 38-16 at the Aviva Stadium.
They advance to the May 12 decider in Bilbao where they will play either provincial rivals Munster or French club Racing 92.
"I thought the players were pretty clinical in terms of taking opportunities when we got into the 22, coming away with points more often than not," Cullen said.
"Clearly when you score early and have a lead, it allows you to be able to manage the game and try to squeeze the opposition that little bit more.
"We've a lot of respect for Scarlets in terms of what they've done in recent times.
While Leigh Halfpenny's unerring boot ensured the Scarlets remained in touch approaching the interval, winger McFadden's try on the stroke of half-time gave Leinster a 24-9 cushion.
Cullen acknowledged this was a crucial moment in the contest and was pleased with the composure shown by his players to close out the game in the second half.
"Ferg's try on half-time was a huge moment I think in the game, but how we managed the second half was important. I thought the guys controlled the game well, played in the right areas and we were just able to put the squeeze on Scarlets and frustrate them.
"They couldn't really get access to our area of the field. It was a big moment (right) on half-time and how we managed the second half then is important," he added.
On his most recent visit to the Aviva Stadium just under 12 months ago, Scarlets boss Wayne Pivac celebrated a magnificent PRO12 final victory over Munster.
However, with Leinster proving too strong as they avenged a PRO12 semi-final defeat from last season, the New Zealander admitted his men were second best on this occasion.
"Leinster fully deserved their win. They were the better side on the day," he said.
"I think it was a mixture of how well they played and probably how well we didn't play.
"I thought they were very direct. They knew that we'd bring a lot of line-speed and I think they did very well to look after the ball in contact," added Pivac, who watched the Munster-bound Tadhg Beirne sign off in European competition for Scarlets with a late consolation try.
"They had good speed of ball which kept us on the back foot and they were just getting that roll on.
"The game of feet and inches they won, and they put us under a lot of pressure. They fully deserve to go through to the final."