A brace from Jamie Vardy and a Youri header, handed 10-man Arsenal their third straight league defeat in a week.
Arsenal went a man down as Aisley Maitland-Niles was sent off in the 36th minute for receiving a second yellow card.
Before the start of the second half, Arsenal made their first change with Alex Iwobi going off for Laurent Koscielny.
Despite holding out going into the break, Arsenal’s resolve was finally broken in the 59th minute as Tielemans broke the deadlock, meeting James Madison’s cross with a powerful header.
In the 86th minute, Vardy made it 2-0, heading in his rebound which initially came off the cross bar.
And in the 95th minute, Vardy grabbed his second goal and Leicester’s third with a simple tap in.
Vardy has now scored more Premier League goals against Arsenal (eight) than any other club in his career.
Arsenal remain fifth on 66 points, just one point off fourth placed Chelsea in the league table with two games to play.