Lyndon Lewis' Drovers were 43-41 winners over Bedwas at the Bridge Field on Saturday, edging a remarkable game in which there were 11 tries in total.
The win means Llandovery secured second spot and although Llanelli failed to win away to Pontypridd, the two sides will now meet at Church Bank to see who will play top side Pontypridd in the play-off final.
The play-off semi-final will be played on the weekend of May 10 with the final scheduled for Saturday, May 18.
And after a thrilling win over Bedwas, Llandovery head coach Lewis was delighted to see his side still in contention for the title.
"It was end to end stuff and the game was a great advert for the Premiership and the play-off system," he said.
"This game might have been a dead rubber but we've had a great crowd and a great game and both sides tried to play attacking rugby. A draw would have been a fair result but we're left happy as we've got the win next to our name."
Lewis' men can now look forward to a clash with Llanelli who were beaten 27-18 by Pontypridd at Sardis Road. Despite the result, Llanelli still did enough to earn third place.
They will take on a Llandovery side who impressed against Bedwas, especially in attack. The centre pairing of Jack Roberts and Matthew Jacobs looked dangerous all day with Roberts crossing for a brace of tries.
James Garland, Lee Rees, Aaron Warren and Chris Knight added further tries to secure the win but Lewis will know his side will have to improve defensively if they are to be crowned champions.
"We'll look forward to it, we always enjoy our games against Llanelli," he said of the upcoming play-off semi-final.
"We've finished second in the league which is a great accolade for us and we'll take huge positives from that."
While Llandovery and Llanelli are still in with a shout of the title, today's results mean Bedwas are now out of contention.
At one stage today, a 31-19 lead over Llandovery looked like being enough to send them into the play-offs.
But it was not to be, though their head coach Steve Law echoed the thoughts of Lewis.
"We are very, very disappointed to lose the game today but we wish Llandovery all the best," he said.
"Everybody was a winner today, it was a very good game and I can't ask any more of my players and squad. They gave it everything and up until the last play of the game, we could still have won it."
In the three other Premiership games to take place today, Aberavon were 33-22 winners over Bridgend at the Talbot Athletic Ground.
Cross Keys got the better of Carmarthen Quins and Neath and Cardiff shared an 18-18 draw at The Gnoll.
Aberavon 33 - 22 Bridgend
Bedwas 41 - 43 Llandovery
Cross Keys 28 - 3 Carmarthen Quins
Neath 18 - 18 Cardiff
Pontypridd 27 - 18 Llanelli