Marcelo Bielsa’s Leeds squandered a host of chances, both before and after Pepe was dismissed after video assistant referee consultation for sticking his head into Ezgjan Alioski’s face.
Substitute Rodrigo, Patrick Bamford and Raphinha – deep into injury time on his first Premier League start – struck the woodwork.
The Gunners were poor – yet again – and Pierre-Emerick Aubameyang’s 60th-minute effort was their first of two shots on target.
They have scored one Premier League goal, an Aubameyang penalty against Manchester United, in five games since 4 October.
Both sides came into the game out of form – with three defeats in their previous four league games.
Leeds boss Marcelo Bielsa will be happy with his side’s performance, bar the finishing, with opposite number Mikel Arteta relieved to pick up a point.
Arsenal remain in the bottom half of the table, moving up to 11th, two points above Leeds in 14th.
Leeds were the first promoted Premier League team to score 14 goals in their opening eight matches since Charlton in 2000.
They could have used some of those goals at Elland Road, with only four of their 25 shots on target.
Their three efforts against the woodwork all came from the 79th minute onwards.
Arteta has helped to solidify their defence, but they have only scored nine goals in nine league games this season. That is their lowest tally at this stage since 1986-87.
Aubameyang got a rare chance to play as their main striker, with Alexandre Lacazette left on the bench – but Arsenal struggled to create many clear-cut chances.
He took an hour to test Illan Meslier, whose only other save was to deny substitute Bukayo Saka late on.
The Gunners did have a penalty appeal when Liam Cooper blocked an Aubameyang shot with his elbow but the VAR team ruled it was not handball.
Arsenal – who only had 33.7% of the ball – were hanging on, especially after Pepe’s red card.
The Ivorian, who has rarely justified his £75m fee, had a running battle with Alioski and eventually lost his patience with a ‘football headbutt’.
Alioski threw himself to the ground and Pepe was sent off for the first time in his career.