If he does it again, close his door until he's in his bed. If your child gets into your bed during the night, order him back to his own bed using a stern voice. If he doesn't move, take him back immediately without talking to him. If your child gets into your bed while you are asleep, take him back to his room as soon as you discover him. If he tries to leave his room again, temporarily close his door.
Some parents simply lock their bedroom door.
Remind your child that it is not polite to wake up people who are sleeping, unless it is an emergency. Expect some crying. Young children normally cry when they don't get their way. But continue to be firm and you will win back the privacy of your bed.