Trevor Phillips has headed the EHRC since it was created in 2006
Chairman of the UK equality body Trevor Phillips "must bear responsibility" for its early problems, says a report.
MPs and peers questioned his role in the "implosion" of the equalities body in 2009 - when six commissioners quit.
They also said the commission's goals were "too vague" and noted that there were eight commissioners with Labour links, one Lib Dem but no Tories.
The commission said it had addressed many of the concerns and its "new, stronger board" was working well.
Separately Mr Phillips faces a parliamentary inquiry over suggestions he tried to influence members of the joint committee on human rights ahead of the report's publication - something he denies.
One of the committee's members, Labour MP Fiona MacTaggart, has criticised its inquiry into the Equality and Human Rights Commission - saying it was more like a "show trial".
But the committee says it decided to use its annual oral evidence session with Mr Phillips to look at "the various problems of leadership and management which had emerged into public view during the year".
The body has 14 commissioners including Mr Phillips. In March 2009 the chief executive, Nicola Brewer, resigned to take up a new post.
There were rumours she did not get on with Mr Phillips but he told the inquiry she left because Ms Brewer, a career diplomat, got her "dream posting" as UK high commissioner to South Africa.
Five other commissioners also quit - Baroness Campbell, Prof Kay Hampton, Prof Francesca Klug, Sir Bert Massie and Ben Summerskill, some of whom openly criticised Mr Phillips's leadership style.
Among criticisms were policy being made "on the hoof", a "divisive culture" on the board and an "atmosphere... of intimidation sometimes in holding the chair to account".
But Mr Phillips was defended during the inquiry by other commissioners and he argued that "passions" and arguments were part of the role of the body.
Equalities Minister Harriet Harman suggested that when the commission was formed - bringing together three old equality bodies - there would always have been problems in bringing together the "different cultures".
But the committee said: "Organisational problems and tensions were inevitable but we are not persuaded that the EHRC's implosion in 2009 was unavoidable."
Merging the three bodies and making best use of the expertise of all its commissioners were "challenging tasks" but they said: "In the early years of the EHRC's existence this was not done successfully, for which the chair must take responsibility."
It noted there were "conflicting accounts" of "tensions" in the board but said a separate review by accountants Deloitte also suggested some problems "stemmed from Mr Phillips' leadership style".
They criticised Ms Harman for reappointing Mr Phillips in the role for another three years without advertising the job - saying open competition would have helped "restore confidence in the organisation and its leadership".
They said the commission itself suffered from a vague strategy - with "few indications of timescales, milestones or measures of success".
It said one commissioner had said "the commission has been responsible for a 'great list of achievements'" adding: "We do not fully share this view".
The strategy should be redrafted to make it "less aspirational and more concrete" and published later this year, the committee said.
And they said there should be at least one commissioner with links to the Conservative Party to enhance "the commission's credibility across the political spectrum".
Mr Phillips was also criticised for taking "some time" to give up a controlling share in a consultancy called Equate, after concerns were raised about a possible conflict of interest.
And the committee said it was "unacceptable" no new chief executive had yet been appointed - the government suspended the recruitment process because of questions over its £185,000-a-year salary.
The commission has been criticised by another committee over its use of public money in rehiring former staff from its predecessors who had received large severance packages.
Committee chairman Andrew Dismore MP told BBC Radio 4's Today programme that now Mr Phillips had been reappointed he had to show "he has got to prove that he can build a cohesive board that operates in a collective way".
He added: "I think part of the problem has been what was called the divisive culture, an attitude of clique-ism, intimidation within the board and hopefully that's now being addressed as identified by a Deloitte report."
He said the human rights strategy published was "a disappointment" and "appears to have been drafted in haste".
Ms Harman was also criticised over Mr Phillips' reappointment
Responding to the report an EHRC spokesman said: "It is disappointing that the committee has allowed itself to be distracted by events dating back to 2006/7 rather than focusing on our record over the last year, and by the comments of a small number of unhappy ex-board members which were rejected by other board members who gave evidence".
He said the body "has addressed many of the concerns about its governance and management since then and they are no longer relevant".
The spokesman said there was "a new, stronger board working positively together" and he cited the protection of people in care homes as an example of the body's "significant human rights achievements".
Ms Harman said she had reappointed Mr Phillips and his deputy chair for a second three-year term because - as the chief executive had resigned and the Equality Bill was going through Parliament - she thought it "important... for the sake of continuity".