The Blues were reduced to 10 men when Moises Caicedo was shown a red card for a rash challenge in the 38th minute, leaving Chelsea to play over half of the match a player down.
Despite this and surrendering over 60% of the possession to the Gunners, they produced twice as many chances and as much xG as the visitors.
Chelsea even took the lead against all expectations shortly after half-time through Trevor Chalobah in the 48th minute.
Mikel Morino rescued a point for Arsenal with a goal in the 59th minute but they will be disappointed not to have taken all three points, given the man advantage they had for most of the game.
Elsewhere in the Premier League on Sunday, Liverpool got back to winning ways with a convincing 2-0 win over West Ham United.
The Reds dominated most of the game, with West Ham only producing .32xG from seven shots.
Despite their dominance, Liverpool had to wait until the 60th minute for Alexander Isak to open the scoring with a neat finish.
The Hammers were reduced to 10 men in the 84th minute when Lucas Paqueta was shown two yellow cards within a minute for arguing with the referee.
Liverpool made the most of their numerical advantage to score a second goal through Cody Gakpo two minutes into stoppage time to secure the three points.
Manchester United recovered from a goal down to beat Crystal Palace 2-1 at Selhurst Park.
Palace were on top for much of the first half and grabbed the lead through a Jean-Philippe Mateta penalty in the 36th minute.
However, United were much better after the break and equalised through Joshua Zirkzee just nine minutes into the second half.
Mason Mount scored the winning goal from a free kick just outside the box in the 63rd minute as United claimed their sixth win of the season and moved back up to seventh place in the standings.
Frank Lampard says leading Coventry City back to the Premier League after a 25-year absence, and then wrapping up the Championship title, is an achievement "right at the top of my career".
Chelsea defender Trevor Chalobah believes the squad must be held accountable for a disappointing performance in the 3-0 loss against Brighton and Hove Albion on Tuesday.
Manchester City midfielder Nico Gonzalez has emphasized that his team must focus on themselves ahead of Premier League clash against Burnley at Turf Moor on Wednesday.
Arsenal's grip on the Premier League summit is under growing threat after a series of damaging results, prompting sharp criticism from former Chelsea midfielder John Obi Mikel.
