Walt Disney Co., in the midst of heated union negotiations on both coasts, has offered to raise the starting pay for its California theme-park workers to $15 an hour over the next three years.

Entry-level employees at Disneyland would see their pay rise to $13.25 an hour immediately from $11 currently and then to $15 by 2020, two years ahead of a deadline set by California. Disneyland and its sister park, California Adventure, employ about 30,000 people in Anaheim, California....