LaCava, who has previously been on the bag for Fred Couples and more recently Dustin Johnson, takes over the role from Steve Williams, who was sacked in July.
"I'm excited to be working with Tiger," LaCava said. "Tiger and I have been friends for a very long time, and I know what he can do.
"I want to thank Dustin for the opportunity to work with him, and I wish him nothing but the best."
LaCava's first tournament with former world number one Woods will be the Frys.com Open in early October.