what should i major in for a bachelors degree if i were to do a masters in mechatronics engineering?

There are universities which have Mechatronics as formal engineering discipline at the undergraduate level. They are usually part of the Mechanical Engineering Department or School. If you can not find one in your area or which you can easily attend, consider going for an Mechanical Engineering or Engineering Mechanics Degree. Be sure to focus heavily on electrical and computer engineering elective courses.

If the school has a robotics area that would also be a good place to focus.

Be sure to talk to a guidance counselor and with your academic adviser when choosing your courses at the undergraduate level.

Niel Leon
engineering.com

Some schools have undergrad mechatronics degrees. If they don't I would go Electrical or mechanical engineering and take robotics classes.