Aki Riihilahti headed Palace in front after 10 minutes, but Ipswich were level before half-time when Tom Soares unluckily deflected into his own goal.
Palace regained the lead seven minutes after the break when Clinton Morrison headed home Ben Watson's free-kick.
Ricardo Fuller nodded in Matt Richards' cross after 67 minutes, but was later sent off for making a gesture at fans.
Ipswich manager Joe Royle:
"Yet again we have finished the game with 10 men and yet again we are puzzled.
"The fans were giving Ricardo a hard time, and in his frustration he stuck two fingers up at them. I don't believe that is a sending-off offence.
"We played the better football and with a bit more luck we might have won."
Crystal Palace: Kiraly, Boyce, Borrowdale (Leigertwood 90), Ward, Fitz Hall, Soares (Freedman 77), Riihilahti, Watson, McAnuff (Reich 87), Johnson, Morrison.
Subs Not Used: Popovic, Speroni.
Goals: Riihilahti 10, Morrison 53. Ipswich: Supple, Wilnis, Richards, De Vos, Sito, Magilton (Brekke-Skard 84), Currie, Garvan, Barron (Casement 68), Lee, Fuller.
Subs Not Used: McDonald, Clarke, Price.
Sent Off: Fuller (78).
Booked: Wilnis, Lee, Fuller.
Goals: Soares 30 og, Fuller 67.
Ref: K Friend (Leicestershire).