Even with a court order of custody, you will likely require the court's permission to move with your child.
Parents who seek relocation are often confronted with unemployment, a stagnant job market, or a local cost of living that is just too high. Other times, there are better economic or educational opportunities elsewhere, or you may need to live with family members in a different part of the country.
On the other hand, you may be the non-custodial parent who is opposed to the other parent's proposed move, which would adversely impact your parental rights and visitation.
The court will consider a variety of factors in considering an application for relocation, including the "best interests of the child."
I have effectively litigated many relocation cases on behalf of my clients.