Priestland levelled again but when Scarlets spilled the ball inside their own half in the 68th minute, Zebo kicked ahead and easily won the race to the touchdown.
It was a victory that secures Munster a home semi final in the Magners League play offs.
Munster: P Warwick; S Zebo, J Murphy, L Mafi, D Barnes; D Cusack, P Stringer; M Horan, M Sherry, S Archer; D Ryan, M O'Driscoll; T O'Donnell, N Ronan, D Leamy capt. Replacements: D Fogarty, D Hurley, J Hayes, A Quinlan, P Butler, D Williams, S Tuitupou, S Deasy.
Scarlets: M Stoddart; G North, R King, G Maule, S Lamont; R Priestland, T Knoyle; I Thomas, M Rees capt, R Thomas; L Reed, J Turnbull; R McCusker, J Edwards, D Lyons. Replacements: E Phillips, R Jones, S Gardiner, A Shingler, D Welch, G Davies, S Jones, S Williams.
Referee: Alan Lewis (Ireland).