The committee said the former foreign secretary failed to register a 20 per cent share of the ownership of a property in Somerset within the 28-day timetable of acquiring it.
It said that the breach followed a previous failure to register a financial interest and demonstrated “an over-casual attitude towards obeying the rules of the House”.
It instructed Mr Johnson to meet with the Registrar of Members’ Financial Interests in person to receive a full briefing from her on his obligations as a MP to register all relevant interests.
The committee added it would consider any further breaches of the rules as a matter which may call for “more serious sanction”.
The Committee noted there was no evidence of any intention to deceive by Mr Johnson, and acknowledged he had made repeated apologies for his breaches the rules.
Mr Johnson acquired the interest in the property in January 2018, but did not register it for another 12 months, saying he had misunderstood the rules relating to the threshold above which an interest has to be declared.
However, the committee noted that it followed an assurance to the Parliamentary Commissioner for Standards Kathryn Stone in October 2018 that his entry in the Register of Members’ Financial Interests was up to date following a previous failure to declare an interest.
The committee said: “We conclude with concern that these two investigations by the commissioner in rapid succession demonstrate a pattern of behaviour by Mr Johnson.
“While there is no suggestion that he has at any time tried deliberately to conceal the extent of his interests, this latest breach reinforces the view which we expressed in our previous report, that he has displayed ‘an over-casual attitude towards obeying the rules of the House’, in conjunction with ‘a lack of effective organisation within (his) office’.
“We find it particularly regrettable that Mr Johnson gave an assurance to the commissioner that his registration of financial interests was up to date, and within a very short period it proved not to be.”
Last December, Mr Johnson apologised to the House after an earlier report by Ms Stone found he had been late in registering financial interests on four previous occasions in the recent past involving nine separate payments.
Ms Stone said: “Mr Johnson has co-operated fully with my inquiry, but his failure to check properly that he brought his register entry up to date during the last inquiry might be regarded as showing a lack of respect for the House’s rules and for the standards system.
“That does not demonstrate the leadership which one would expect of a long-standing and senior Member of the House, nor compliance with the general principles of conduct.”