The Blues got off to a slow start and went behind inside 10 minutes when David McGoldrick flicked home Sander Berge's shot to wrong-foot Edouard Mendy. However, the Londoners found themselves ahead before half-time, and they never looked like conceding the points thereafter.
First, Tammy Abraham equalised with a mis-hit shot from Mateo Kovacic's cut back, before Ben Chilwell made the most of Aaron Ramsdale's failure to collect 's free kick, and bundled home at the back post. Then, in the second half, Thiago Silva headed Chelsea's third before Timo Werner added the icing on the cake.
Chelsea have now scored three or more goals in six of their past eight games. The visitors were tough to break down with two banks of three, but the Blues found a way through, first through wide positions, before the game opened up.
There was very little to criticise about Chelsea's performance, though they conceded their first goal in five games. The Blades caught the Blues' defence napping and carved them open, but it was a mere blip as the home side then went through the gears.
Manager rating out of 10
8 -- Frank Lampard will be very pleased with his side's work, particularly with how his new players continue to grow with every match. Ziyech impressed in particular on the night, but Werner and Silva also played well. It all seems to be coming together for the Blues manager.
Player ratings (1-10; 10 = best, players introduced after 70 minutes get no rating)
GK Edouard Mendy, 6 -- Conceded his first Premier League goal, but could do little to prevent McGoldrick's flick from finding the net after the Republic of Ireland international converted Berge's shot into the opposite corner.
DF Reece James, 8 -- Another solid outing in which he rarely gave the ball away or lost out on the floor or in the air. He looks dangerous at both ends, and appears to be getting better with every game.
DF Kurt Zouma, 7 -- Zouma looks a class act when playing alongside Silva. After a slow start, he showed great composure on the ball and won everything thrown his way in the air.
DF Thiago Silva, 8 -- It's no coincidence that Chelsea look more solid when Silva partners Zouma, and although they endured a rough start as the visitors took the lead, Silva was superb, and even got on the scoresheet with a header 13 minutes from time.
DF Ben Chilwell, 7 -- The left-back gave another assured performance. As well as looking solid at the back, he gave Chelsea the lead when he bundled home at the back post after Ramsdale failed to collect.
MF Mateo Kovacic, 7 -- Arguably his best game of the season so far. He made a clever run between the lines before crossing to Abraham for Chelsea's equaliser, and he ran himself into the ground before coming off after 70 minutes.
MF N'Golo Kante, 7 -- The midfielder played deep and did what he does best: winning the ball and playing the simple pass to his teammates. He then edged further forward when Jorginho came on.
MF Mason Mount, 7 -- Mount was excellent in Chelsea's midfield. His long-range passing was superb, though he needs to work harder on beating the first man at a corner.
FW Hakim Ziyech, 9 -- A constant menace all game, displaying an incredible array of passing. He was involved in the first three goals, the second involving a wicked delivery that was finished by Chilwell. He created chances from wide and deep.
FW Tammy Abraham, 7 -- Levelled the score with his second goal in a week. His equaliser was a scuffed effort, but it was directed accurately into the corner. It was his fourth goal in four games against the Blades.
FW Timo Werner, 7 -- He came to life in the second half, first missing the target with a lobbed effort resulting from an exquisite ball from Ziyech, but he made no mistake moments later to score Chelsea's fourth.
MF Jorginho, N/R -- Came on with 19 minutes remaining and sat in front of the Chelsea defence to push Kante further forward.