Rhys Priestland and Ronan O'Gara swopped penalties and Munster had to wait until the 38th minute of the half before they had their second try from David Wallace - at a time when they were reduced to 14 after Earls had been yellow-carded.
Scarlets clawed their way back into the game with a Martin Roberts try in the 46th minute converted by replacement Robert Jones but Munster mustered enough momentum to score further tries from Keith Earls and Denis Leamy to earn themselves the bonus point and keep themselves on track for the title.
Munster: P Warwick; D Howlett, K Earls, L Mafi, I Dowling; R O Gara capt, T OLeary; M Horan, J Flannery, J Hayes, D OCallaghan, M ODriscoll, A Quinlan, D Wallace, D Leamy. Replacements: D Fogarty, T Buckley, D Ryan, N Ronan, P Stringer, B Murphy, D Hurley.
Scarlets: D Evans; M Jones (capt), R Higgitt, J Davies, L Williams; R Priestland, M Roberts; I Thomas, M Schwalger, S Roberts, V Cooper, D Day, J Turnbull, R McCusker, D Lyons. Replacements: P John, M Rees, A Shingler, J Edwards, G Cattle, S Jones, C Thomas.
Referee: Neil Paterson (SRU).