Gareth McAuley got both the goals to ease Leicester's relegation fears and seal their first win since Boxing Day as 10-man Ipswich slumped at home.
Jaime Peters had been denied superbly by Foxes keeper Paul Henderson when the visitors took the lead, McAuley heading home Levi Porter's corner unmarked.
And the defender repeated the feat from Mark Yeates's cross on 55 minutes.
Peters went close again for Ipswich before Owen Garvan was dismissed for a second bookable offence on 69 minutes.
606 DEBATE: Give your thoughts on this encounter
Ipswich coach Bryan Klug on Owen Garvan's red card:
"I thought the referee got it spot on.
"There's no point hanging someone out to dry over the goals. It was poor defending.
"It's a collective thing here, but that's the second game in a row and it's reared its ugly head at other times this season and it's avoidable."
Leicester manager Rob Kelly:
"We've not had the best of times here over the last 20 years or so.
"It's a tough place to come but I though we deserved to win. I've got a great
bunch of lads here but they wanted support and to be pushed, and so I'm
delighted to have got two or three players in.
"This is traditionally a difficult place to come but these players don't
skulk away. They come out and say 'let's have a go'."
Ipswich: Price, Wright, Wilnis, Bruce, Harding, Peters, Garvan, Legwinski (O'Callaghan 67), Currie, Walters, Clarke (Haynes 67).
Subs Not Used: Supple, Richards, Sito.
Sent Off: Garvan (69).
Leicester: Henderson, Maybury, Kisnorbo, McAuley, Johansson, Porter, Jarrett, Johnson, Yeates (Glombard 83), Hume (Hammond 79), Horsfield (Kenton 90).
Subs Not Used: Logan, Stearman.
Goals: McAuley 28, 56.
Ref: C Boyeson (E Yorkshire).