Preston were unchanged from their 4-0 win at Coventry, but put in a below-par performance to dash their play-off hopes and ease Leicester's relegation worries.
Leicester captain Patrick Kisnorbo had a ten-yard header saved in the 12th minute.
The first corner came for Preston after 23 minutes and the home side could only manage the one shot over the bar in the whole of the first half by Danny Pugh.
Iain Hume had a right-foot volley saved and Stephen Hughes had a 25-yard right-foot shot also saved.
Shaun Newton shot over the bar and James Wesolowski narrowly shot wide of the keeper's left-hand post.
Hume was booked two minutes into the second half for a foul on Matt Hill.
Liam Chilvers had a ten-yard header which went wide from a Graham Alexander free-kick.
David Nugent had an eight-yard right-foot volley saved by Conrad Logan at the second attempt.
Chilvers was booked for a foul on Matty Fryatt and Newton was booked for a foul on Nugent.
Newton fouled Callum Davidson 25 yards out and Alexander hit a right-foot free-kick which was deflected over the bar for a corner.
Foxes boss Nigel Worthington brought on Danny Cadamarteri for Fryatt after 61 minutes and Preston brought on all three substitutes as Paul Simpson made wholesale changes.
Preston had a scare with two minutes left when Hume hit a 25-yard right-foot shot against the keeper's left-hand post.
Then, in the last minute, a Newton right-wing free kick was met by Johansson and he hit a close range left-foot volley into the top corner of the net to steal all three points for Leicester.