As well as Harris, the Bluebirds have parted company with assistant manager David Livermore.
This decision comes after Cardiff suffered a 1-0 defeat at home to Queens Park Rangers on Wednesday, meaning that they have now lost five league games in a row for the first time since October 2018, when they were in the Premier League.
Following the sacking of both senior members of the management team, club owner Tan Sri Vincent Tan said: “I would like to thank Neil and David sincerely for their hard work at Cardiff City.
“Their efforts to propel us towards a fifth-place finish and play-off position last year are recognised and appreciated.
"Although sadly we are in a result-orientated business and our on-field results of late and progress this season has been very poor.
"As such, we have had no choice but to relieve them of their duties in an effort to improve results and league position with a change of manager.
“I would like to personally wish Neil and David the very best with their future undertakings and endeavours.
"They will always be welcome faces at Cardiff City Stadium and I wish them good luck and good health.”
Harris' time at Cardiff
When he took over, Cardiff were positioned 13th in the Championship table after 13 games. but after accumulating an impressive 55 points from 28 games, he managed to guide the club to a fifth place finish.
However, the Bluebirds fell just short in the play-offs after losing narrowly 3-2 on aggregate to eventually promoted Fulham.
Then in the current campaign, despite Cardiff being only three points behind the play-off places in tenth position in mid-December, five consecutive league defeats and six losses in a row have left Cardiff in 15th place, 13 points adrift of the top six.
Was Harris' sacking justified?
Despite there being no doubt that the 43-year-old has had a good stint at the club, football is a results-driven business and losing six in a row in all competitions is simply not good enough.
Especially considering the calibre of players that the Bluebirds have under their ranks and the fact that they finished in the play-offs last season, at the start of this campaign the club would have been expecting to contend for another top six finish.
However, due to a poor run of form, even with 22 games remaining, the possibility of achieving this seems unlikely and ultimately that has to be put down to Harris.
Who is in the running to take over?
According to The Sack Race, following the departure of Harris, at the time of writing former Wolverhampton Wanderers and Republic of Ireland manager Mick McCarthy and ex Wigan Atheltic and Portsmouth manager Paul Cook are 4/1 favourites to take over the vacant job.
Ultimately Cardiff will just be looking for someone to steady the ship and help them find a bit more consistent form until the end of the campaign.
Then next season they will hope that they can back on track and begin battling for a spot in the play-offs once again.