Ms Patel was accused of demeaning her staff by shouting and swearing at them, which resulted in Mr Johnson launching an inquiry in March. The Prime Minister’s independent standards adviser, Sir Alex Mr Allan found that Ms Patel had become “justifiably in many instances” frustrated by her department’s lack of support, and this had “manifested itself in forceful expression, including some occasions of shouting and swearing”.
He said: “Her approach on occasions has amounted to behaviour that can be described as bullying in terms of the impact felt by individuals.
“To that extent her behaviour has been in breach of the Ministerial Code, even if unintentionally.”
He concluded Ms Patel had not met the standards set under the UK’s Ministerial Code which states ministers should treat officials with respect.
Ministers usually step down if they are found to be in breach of the code.
However, a Government statement said Mr Johnson believed the code had not been breached.
It added that concerns had not been raised at the time and that Ms Patel was unaware of the impact of her actions.
The statement said: “The Prime Minister has full confidence in the home secretary and considers this matter now closed.”
Ms Patel apologised and said it had never been her intention to upset anyone.
He said: “I recognise that it is for the prime minister to make a judgment on whether actions by a minister amount to a breach of the Ministerial Code.
“But I feel that it is right that I should now resign from my position.”
Downing Street added Mr Johnson has “full confidence” in the Home Secretary and “considers this matter now closed”.
It comes after Mr Johnson wrote in the foreword to the Ministerial Code’s latest version that “there must be no bullying and no harassment”.
A Cabinet Office report was launched eight months ago after it was alleged Ms Patel clashed with senior officials in three separate departments.
It was triggered after former Home Office’s permanent secretary Sir Philip Rutnam resigned in February.
He accused Ms Patel of a “vicious and orchestrated briefing campaign” against him and claimed constructive dismissal at an employment tribunal.
Ms Patel responded by calling the claims “false”.