Mourinho was ordered from the technical area by referee Anthony Taylor with 20 minutes of the match at Stamford Bridge remaining and clambered over the dugout and into a spare seat in the area behind, next to Blues fan Sean Buxton.
He later tweeted a picture of himself sat next to the Blues manager, saying: "OMG morinho is sitting next to me wtf!!!!!" before adding: "He's taking the p*** with the leg room".
The picture had been retweeted over 7,000 times within half an hour of the game ending.
The crowd chanted Mourinho's name after his sending-off before expanding the song to "Jose Mourinho, he sits where he wants".
Mourinho deferred to assistant Steve Holland for post-match media duties and the latter insisted the Portuguese was right to be frustrated by the perceived time-wasting of Cardiff.
"His frustration was clear and, in my opinion, totally justified," Holland said.
"Why would it take an hour before finally an issue was addressed? He showed his frustration and then was sent to the stands."
Mourinho and Holland told fourth official Trevor Kettle of their unhappiness with Cardiff's tactics on "countless occasions", without it being acted upon.
On the controversial equaliser, Holland said: "From my point of view, it looked to me like the goalkeeper was bouncing the ball.
"The referee had a very clear view of it and was happy with it and we move on.
"Over the course of the season, those things go one way or another for you."
Holland praised Chelsea for responding to a defensive lapse which allowed Mutch to put Cardiff in front, when David Luiz left the ball for Petr Cech, who was making his 300th Premier League appearance.
"It wasn't a good start for us," the assistant boss said.
"The players responded very well from that."
Eto'o scored his first Chelsea goal on his sixth appearance in the second half and Holland hopes for more at Schalke in Tuesday's Champions League Group E clash.
Holland said: "All strikers like to be scoring goals. It's what helps to make them tick and to get off the mark will I'm sure be something he's very, very happy about. Hopefully we get the benefit of it immediately."
But it was visiting boss Malky Mackay who felt he had greater reason to feel aggrieved after a refereeing error at Stamford Bridge.
Chelsea cancelled out the Cardiff opener, scored by Jordon Mutch, when Eto'o robbed David Marshall as the goalkeeper bounced the ball, and Eden Hazard netted.
Following the match, Mackay approached referee Anthony Taylor about the incident, but prior to viewing the replay.
"I've got to be careful what I say, because I'm certainly not intending having money taken from me," Mackay said.
"I did go in to ask for clarification of the ruling and what the referee and linesman saw.
"The explanation leaves me really disappointed, because I've since looked at it and the explanation was that they felt the goalkeeper dropped the ball.
"My goalkeeper bounced the ball. He saw Samuel Eto'o standing next to him and he bounced the ball.
"They (the match officials) thought he didn't have the ball in his control and he dropped it and the ball was in open play. That's a mistake."
Mackay asked if a foul would have been awarded if Marshall had been bouncing - and therefore in control of - the ball and was told yes by the officials.
Asked why Marshall chose to bounce the ball with Eto'o lurking, Mackay said: "Because he's allowed to bounce the ball and Eto'o's not allowed to touch the ball."
Mackay added: "(Marshall) said he saw Eto'o standing next to him and he knows the rule. He knows he's allowed to bounce the ball and that's why he bounced it."
Chelsea went on to claim an emphatic win, with Eto'o scoring his first Blues goal and substitute Oscar and Hazard adding to the score