Goals from Jamie Vardy and Harry Maguire were enough for Leicester to secure a 2-0 victory at winless Newcastle.
Vardy broke the deadlock from the penalty spot on the half-hour mark to net his second goal in as many games after returning from suspension, giving his side the lead going into the interval.
Newcastle owner Mike Ashley was in the stands for the first time in 16 months - on the day Peter Kenyon was reported to be plotting a takeover bid for the club - but he could only look on as Maguire made sure of the away victory in the 73rd minute.
The final whistle was greeted by a chorus of boos from all around St James' Park as Newcastle remain in the bottom three, having lost their first four home league games for the first time in their history. Leicester are up to seventh after their second successive league win.
Newcastle: Dubravka (6), Clark (5), Lascelles (6), Yedlin (4), Diame (5), Ritchie (5), Atsu (6), Shelvey (6), Kenedy (5), Perez (5), Joselu (3).
Subs: Muto (6), Murphy (6), Manquillo (N/A)
Leicester: Schmeichel (7), Chilwell (7), Morgan (7), Mendy (6), Maguire (7), Amartey (6), Ndidi (7), Pereira (7), Maddison (8), Vardy (7), Iheanacho (7).
Subs: Albrighton (6), Iborra (N/A).
Man of the match: James Maddison
The home side had the better of the opening exchanges, with Ayoze Perez denied by a fine block from Wilfred Ndidi, before the same man played in Joselu, who delayed far too long before Maguire slid in to make the interception.
Mo Diame then headed wide from a good position, before Newcastle were masters of their own downfall once more, with DeAndre Yedlin handling in the box to concede a 30th-minute penalty.
Vardy stepped up to fire an unstoppable penalty past the despairing dive of Martin Dubravka in the Newcastle goal, increasing the feeling of vitriol around St James' yet further.
As expected, Salomon Rondon missed out through injury, with Joselu leading the line for Newcastle. Ciaran Clark in for Federico Fernandez was the only other change for the home side. The only change for Leicester from their win over Huddersfield last weekend saw skipper Wes Morgan back in the side after serving a one-match suspension, with Jonny Evans dropping to the bench.
After the break, Newcastle continued to offer very little as an attacking force, with Leicester firmly in command despite their narrow advantage in the scoreline.
Maguire, who had earlier embarrassingly missed two attempts to volley for goal, then made sure of the three points for Leicester, heading home from an inch-perfect James Maddison corner.
Newcastle had a few half chances to at least make a game of it late on, with Joselu missing the most threatening opportunity, but his wayward finish summed the home side up, as it appears fans in the north east are in for a long season of struggle.
Notes for Southgate
The England coach was in the stands, and will feel justified in his decision to journey to the north east. Harry Maguire got on the scoresheet and was resolute in defence, while James Maddison showed why he is tipped for the top by so many. Jonjo Shelvey will want to forget this game in a hurry, however.
- Leicester have won three consecutive away games in all competitions against Newcastle for the first time since November 1965.
- Since the start of last season, no team has lost more home Premier League games than Newcastle (11, level with Huddersfield).
- Newcastle failed to land a single shot on target against Leicester in the second half.
- Leicester's James Maddison has been directly involved in five goals in his last six Premier League games (three goals, two assists).
- Leicester City's Harry Maguire has scored two goals in seven Premier League appearances this season, the same total he bagged in 38 games for the Foxes in 2017-18.
Man of the match - James Maddison
The highly-rated youngster's touch was a class apart at St James'. Having created five chances for team-mates in the match - one more than Newcastle created as a team - Maddison will have given England coach Gareth Southgate, sat in the St James' Directors' Box, plenty to ponder. Maddison's cross for Maguire's second was absolutely sublime.
The Pundit - Paul Merson
"Newcastle looked lost. No energy, no pace. They never looked like getting back in the game, and that's not Newcastle. I can't remember Schmeichel making one save. Their one shot on target was when Shelvey tried to lob him from 60 yards - he got back and he caught it.
"Worrying, worrying times for Newcastle. The crowd went mad when Ritchie went off, and for Shelvey, when he looks up, there's nobody making runs. That's a problem, and he's finding it hard now. I think they're in big, big trouble.
"I think Benitez is hanging on in there. I think he could be in trouble in a couple of weeks - I really do. I can't believe what I watched today."
It is a trip to Old Trafford to take on Manchester United for Newcastle next, while Leicester welcome Everton to the King Power Stadium.