An early goal by Mark Bradley and a terrific second-half strike by Mitchell Rose were the highlights of a 2-0 win for the Millers at Livingston.
Right back Bradley converted a free kick by Michael Tidser, sidefooting the ball home in the 10th minute.
Rose, playing wide on the right, smashed the ball into the net from the edge of the box on 76 minutes.
Rotherham had other chances as they kept their pre-season unbeaten record and improved on the 0-0 draw with Greenock Morton on Tuesday.
Once again manager Steve Evans utilised his squad: he made 10 changes at half time.
The starting line-up included for the first time Claude Davis, after a bereavement in his family during the close season.
Bradley and Tidser missed half-chances in the first half.
Strikers Danny Hylton and Kieran Agard were given their chance in the second-half, and both could have increased the lead.
The Livingston keeper denied Ben Pringle but was well beaten by Rose’s goal.
Livingston: Jamieson (Walker 67), Mampuya (Mullen 67), Talbot, Mensing, Fordyce, Beaumont, Trialist (Downie 60), O’Brien (Trialist 80), McNulty, Burchill, McDonald.
Millers first half: Collin, Bradley, Arnason, Davis, Skarz, Worrall, O’Connor, Tidser, Milsom, Revell, Nardiello.
Millers second half: Shearer, Brindley, Morgan, Mullins, Skarz (Rowe 70), Rose, Frecklington, Noble, Pringle (Walker 80), Hylton, Agard.