The lone goal on the day came off the boot of winger Ismaila Sarr, who chipped Ipswich goalkeeper Alex Palmer from close range after playing a lovely one-two pass with Daichi Kamada on the edge of the box.
Palace move up to 11th in the standings with the win, one point ahead of 12th place Brentford and seven points shy of European soccer next season.
Fellow U.S. international Matt Turner went unused as the backup goalkeeper on the bench.