Mikel struck six minutes from fulltime against Fulham with a close-range half-volley after Oscar had opened the scoring early in the second half at Stamford Bridge.
The three points took Jose Mourinho’s team to the top of the table, after a testing period in which they lost to Bayern Munich in the Uefa Super Cup final and were beaten by Everton and Basle.
Mourinho made a big statement with his team selection, with Juan Mata and David Luiz left out of the matchday squad altogether.
Fulham, with three ex-Chelsea players in their midfield – Scott Parker, Damien Duff and Steve Sidwell – had the best of the early chances.
Duff made ground on the right flank and when the ball broke to Alex Kacaniklic, he crossed for Sidwell to head just over the crossbar.
Darren Bent had a clearer opportunity when Pajtim Kasami played him clean through on goal, but his tame shot enabled goalkeeper Petr Cech to make a comfortable save.
Chelsea had an early chance through Samuel Eto’o, who volleyed over from close range as he stretched for Branislav Ivanovic’s cross. The Cameroon striker also had an effort deflected wide.
Eden Hazard had a penalty appeal waved away when he went down under a challenge from behind by Sascha Riether, with Chelsea growing into the game and starting to take control.
Just before the interval, Hazard’s pass found Ivanovic unmarked and his shot was saved by David Stockdale and rebounded to safety off Kieran Richardson.
Oscar’s scrappy opener arrived seven minutes after the break. Stockdale parried from Andre Schurrle and then Eto’o, before Oscar turned the ball in from close range for his second goal of the week.
Sidwell should have equalised when he was found in the box from a free-kick, but the ball had only just cleared the head of teammate Brede Hangeland and Sidwell looked shocked as the ball hit him and spooned wide.
Mourinho took off Eto’o for Fernando Torres, while Fulham tried to change their fortunes in attack by bringing on Adel Taarabt and youngster Buomesca Tue Na Bangna, another one of their former Chelsea players.
Torres forced a fantastic save from Stockdale when his header from a corner was acrobatically tipped over the bar by the Fulham goalkeeper.
Mikel’s rare strike also came from a corner, with John Terry heading the ball down for the Nigeria international to hook home his first Premier League goal in his 185th appearance.
Chelsea owner Roman Abramovich, pictured in the stands, smiled as he celebrated the goal, having looked less than amused when caught on television earlier in the game.
Both sides are in action in the League Cup third round on Tuesday, with Chelsea visiting third-tier Swindon Town and Fulham hosting top-flight rivals Everton.