Allegra Stratton, a former BBC and ITV journalist, publicly apologised for her behaviour which was filmed as she conducted a mock news conference last December.
Video footage of the then Downing Street aide, which emerged earlier this week, saw the row over the alleged party escalate.
Even Tory MPs have expressed anger at her joking while the country was under lockdown.
Ms Stratton announced her resignation outside her London home.
The drama unfolded just two hours after the Prime Minister had told MPs he was “furious” about her conduct. She said: “My remarks seemed to make light of the rules – rules people were doing everything to obey. That was never my intention.
Continue reading your story on the app
Continue reading your story in the newspaper
Moscow in ‘panic plot' to blackmail West, say leaders
VLADIMIR Putin is trying to “sow fear and panic” by destabilising Ukraine to blackmail the West, Kiev warned yesterday.
Feud what feud? says TV Holly
Holly: I couldn’t work with Phillip if he drove me nuts
Cricket boss: I'm sorry for saying black youngsters prefer football
A CRICKET boss has apologised after claiming some ethnic minority youngsters were turning their back on the sport.
‘Mild bug' Elton puts off shows
Positive... Elton John
‘Living with virus' plan soon, says Javid
Hopeful... Javid yesterday
‘Colston clarity is required'
£4.3bn stolen from taxpayers is the real Covid scandal
BORIS'S lockdown birthday cake might have spawned more headlines but the truly shocking story this week is the resignation of Lord Agnew over the colossal loss of taxpayers' money to fraudsters during the Government's "Bounce Back" loan scheme.
Unilever and the Royal Mail slash 2,200 jobs to beat inflation squeeze
UNILEVER and Royal Mail have announced a combined 2,200 job cuts as both look to cut costs and make themselves more efficient as inflation bites.
Star: care axe hits council
Murdered... Star Hobson
Get tough or Russia will never back off, says Brown
Warning...Brown knows Putin