The fight began at a furious pace as the Kazakh pinned Shields up against the tropes before unleashing a torrent of abuse.
Volnova continued to come forward and they went to war once more, trading blows this time in the centre of the ring.
Shields was rewarded for her greater accuracy by the judges, who scored the stanza two points in her favour.
The action was not as fast-paced in the second round. Shields landed with a few decent shots at range to keep the scoreboard ticking over.
Volnova stormed forward early in the third round but walked onto a couple of big punches, forcing the referee to intervene and give her a standing count.
The American had dominated the contest and led by nine points as they entered the final round. She enforced another standing count on Volnova with a heavy right hand.
The judges awarded her a 29-15 decision.