Conservative Party co-chairman Baroness Warsi has been cleared of any serious breach of the ministerial code over an official trip to Pakistan.
The prime minister's adviser found she was guilty of only a "minor" breach for failing to declare she had been accompanied by her business partner.
Lady Warsi, who has apologised to David Cameron, said it was time to "move on".
She is still facing a separate probe by a parliamentary watchdog over her claim for an accommodation allowance.
In a statement, Lady Warsi, said: "I have always maintained that I have never misused my ministerial office for personal or financial gain. The allegations on this matter were untrue and unsubstantiated, and I am pleased that Sir Alex Allan's [Mr Cameron's ministerial code adviser] report has confirmed that.
"The last month has been a difficult time for me and my family and I am pleased I can now move on from this period and get on with the job that I am privileged to do."
Mr Cameron said he was satisfied the report by Sir Alex had found Lady Warsi did not at any point use her office for personal financial gain.
In July 2010, Lady Warsi was accompanied on a visit to Pakistan by Abid Hussain, a second cousin of her husband.
The three of them had set up a restaurant supply company called Rupert's Recipes in 2009. Baroness Warsi had been a director of the company but gave this up when she accepted ministerial office in May 2010.
Both Baroness Warsi and Mr Hussain explained to Sir Alex that Rupert's Recipes does no business in Pakistan, nor had supply contracts there.
In his report, Sir Alex said: "Baroness Warsi has accepted that she should have made officials aware of her business relationship with Mr Hussain, and has apologised for the oversight.
"But, as she says, this was not a trade-related visit; Rupert's Recipes does not do any business in Pakistan and there was no financial benefit to either Baroness Warsi or Mr Hussain; Mr Hussain was not a member of the official delegation, no part of his travel or other costs were met by the British government, and no arrangements were made by her office or the British High Commission for Mr Hussain to meet leading politicians."
He added: "I am satisfied that, had she declared her business relationship, that would not have been seen as a barrier to Mr Hussain helping to organise the visit. Nonetheless, she should have been more aware of the perception of a conflict of interest, and the potential criticism which could arise."
Sir Alex advised the prime minister: "Any action you decide to take in the light of the facts of this case is of course a matter for you, but I record my view that the breach of the code was a minor one, and that Baroness Warsi did not use her office for personal financial gain."
For Labour Michael Dugher, shadow minister without portfolio, said: "Sir Alex Allen's verdict that Baroness Warsi did break the ministerial code is no surprise.
"Nor is the fact that David Cameron has been quick to seize on his words in an attempt to clear her, even though the serious allegations over her House of Lords expenses are still under investigation."