"Mark is a seasoned leader and is going to be an excellent addition to our senior management team," said Apple chief executive Steve Jobs.
The move is the latest chapter in Papermaster's already controversial departure from IBM.
The company filed suit last week for breach of a non-compete agreement on learning that the former blade server development vice president was leaving IBM to join Apple.
IBM claims that Papermaster's status at the company has made him privy to a number of company secrets and that his departure to Apple could give valuable corporate information to a direct competitor.
Big Blue contends that Papermaster's knowledge of its server operations and Power processor unit could be leveraged by Apple in its XServe line of server systems, putting him in violation of a one-year non-compete agreement he signed several years ago.