Llandovery were actually first on the board via a James Garland penalty but the home side soon struck back with the ball moved across the line for prop Ian George to cross for his first Bedwas try. Richard Powell converted.
Bedwas' momentum was then interrupted when they lost hooker Richard Wilkes to injury and two minutes later, Llandovery centre Craig Woodall was on the end of a well worked move for a try converted by Garland.
Both sides battled hard to gain supremacy in a tight encounter but in the run up to half time, Bedwas struck a vital blow.
Wing Rory Budina showed his trademark turn of pace to cross for a quick-fire double and with Powell converting the second of those scores, Bedwas went into the interval with a comfortable lead.
Given a shock at the end of the first half, Llandovery fought hard to get back into the game but could not turn pressure into points. Both sides made changes as the intensity of the game and the heavy pitch took its toll, but Llandovery's only reward was a further Garland penalty after 55 minutes as Bedwas eased home.
In the other games to take place, Bridgend Ravens claimed what could be a vital home win over Cardiff. Ben Rose's side have been at the wrong end of the table for most of the season but their comfortable 26-5 win means they are now 11 points clear of Swansea at the bottom.
Llandovery's defeat at Bedwas was good news for Cross Keys who were also winners on Friday night. Keys have been formidable at Pandy Park in this campaign with Llanelli the latest to return from Gwent with their tails between their legs.
In what was another tight affair, Keys led 6-3 at the break via a drop goal and penalty from Dorian Jones. The Keys fly half has been in good form of late, claiming the Principality Premiership player of the month award before Christmas, and two more penalties and a second drop goal were enough to down Llanelli. Keys are now just four points behind Llandovery in third but have two games in hand on the Church Bank outfit.
The weekend's final encounter saw Carmarthen Quins return to the top of the table with a 16-3 defeat of bottom club Swansea. The Quins did all the damage before half time, an Ellis Phillips try and three penalties and a conversion from Craig Evans opening up a 16-0 lead.
The home side failed to score after the break but the result was never in doubt.
Pontypridd's home clash with Neath on Friday night fell victim to the wet weather and will be replayed at a later date.
Principality Premiership results:
Bridgend 26-5 Cardiff
Cross Keys 15-10 Llanelli
Pontypridd v Neath POSTPONED
Bedwas 19-13 Llandovery
Carmarthen Quins 16-3 Swansea