GOP holdout Jeff Flake of Arizona also said that he would vote to confirm Kavanaugh "unless something big changed."
Earlier in the day, the Senate completed a cloture vote to advance Kavanaugh to final confirmation, which Manchin broke ranks and voted in favor of.
Most senators sat at their desk as the dramatic roll call unfolded, with major suspense over where Murkowski, Manchin and Flake would land. Collins was the first swing vote to support Kavanaugh on the procedural roll call, quickly followed by Flake. Murkowski then inaudibly voted no, a jarring defection that left Republicans with no room for error.