During City's last home game Walker had tussles with a home fan who had invaded the pitch during Leicester's 5-0 hammering by Aston Villa. And this time he literally threw away his side's lead with one of the goalkeeping howlers of the season.
City began in desperate form, without a win in their previous twelve games, while Bolton were looking to stretch and unbeaten run to five.
It was Bolton who created the first threat when a long free-kick by Ivan Campo was allowed to reach Youri Djorkaeff who turned and shot from close range with Walker saving with his legs.
Steffen Freund, making his home debut, then shot wide from 25 yards.
But Bolton continued in the ascendancy and Henrik Pedersen would have been disappointed to have sliced his shot wide after he was teed up by Kevin Davies.
Steve Guppy then hit back with a free-kick to the far post which Marcus Bent headed wide.
But City were given just the lift they needed on 16 minutes with Les Ferdinand grabbing his tenth goal of the season.
Riccardo Scimeca crossed from the right and the 37-year-old powered in a close-range header which Jussi Jaaskelainen parried, but the ball was clearly already over the line before the keeper had reacted.
The confidence so often absent from Leicester in recent weeks now began to flow and Ferdinand had another chance on 23 minutes, but failed to get enough power and direction on a Guppy cross.
But they then had a narrow escape on the half-hour mark when Walker failed to come for a deep Djorkaeff free-kick which Kevin Nolan shot against the outside of the far post.
There was much worse to come for Walker on 33 minutes, this time committing what could turn out to be the biggest goalkeeping mistake of the season.
Davies got a faint touch to another Djorkaeff free-kick which Walker appeared to have gathered safely.
But then he somehow allowed the ball to squirm free from his grasp and hit his leg before rolling over the line.
The tannoy announcer credited Davies with the goal but it was difficult to see how it could be anything else but an own goal by Walker.
Guppy and then Lilian Nalis went close with close-range efforts, but all the talk at half-time was of Walker's blunder.
City almost regained the lead within seconds of the restart when Jamie Scowcroft controlled a Ferdinand flick on, but crashed his 12-yard shot over the bar.
Leicester continued to press with Paul Dickov testing the keeper with an overhead kick and moments later Jaaskelainen did even better when he was at full stretch to keep out the same player's snap shot from three yards.
Ferdinand was again in the thick of the action, this time glancing a Guppy corner wide of the mark.
Then substitute Callum Davidson went close to giving City the win they deserved, but his 25-yard low drive flew narrowly wide.
Leicester: Walker, Scimeca, Dabizas, Taggart, Thatcher, Bent (Scowcroft 36), Freund, Nalis (Davidson 76), Guppy (Stewart 83), Ferdinand, Dickov. Subs Not Used: Coyne, Sinclair.
Booked: Thatcher.
Bolton: Jaaskelainen, Barness, N'Gotty, Thome, Charlton, Nolan, Frandsen, Campo, Pedersen, Davies, Djorkaeff (Javi Moreno 81). Subs Not Used: Poole, Ba, Otsemobor, Vaz Te.
Booked: Nolan, Davies.
Attendance: 26,674
Referee: U Rennie (S Yorkshire)