After bowling the hosts out for 165 at Queens Sport Club in Bulawayo, South Africa cruised to a comfortable victory inside 28 overs to wrap up a 3-0 series success.
Having batted first in each of the first two ODIs, Thursday saw a change for the tourists, only for them to claim a similarly efficient result.
With regular captain AB de Villiers rested with the series already won, Faf du Plessis took over skipper's duties and got off to a good start by winning the toss.
South Africa fielded two debutants in Rilee Rossouw and Mthokozisi Shezi, and Du Plessis' decision looked to be the right one as Zimbabwe openers Hamilton Masakdza (four) and Richmond Mutumbami (zero) both fell early.
Elton Chigumbura and and Sikandar Raza set about rebuilding the innings, adding 51 before the latter departed for 30 off 27 balls.
From that point, captain Chigumbura struggled for support, with Sean Williams (17) the only other man to reach double figures.
With Marchant de Lange returning 3-31 off 7.5 overs and Kyle Abbott 2-21 off six, Chigumbura was the last man out in the 40th over for a well-made 90 off 122 deliveries, featuring 10 boundaries and two sixes.
Roussow made an inauspicious start to his international career, attempting a single to mid-off from his first delivery, only to be run out fora duck by a direct hit from Malcolm Waller.
That apart, it was serene progress for the tourists as De Kock and Du Plessis added 73 in 12 overs before the latter was bowled by Williams (1-1 off two) for 40.
De Kock departed with 22 still required, but JP Duminy (28 not out) and David Miller (13 not out) were able to see South Africa comfortably home, Duminy sealing success with a six over midwicket.