The comments were made by Labour MP Steve Rotheram after the Home Secretary agreed to the disclosure during a Commons debate on Monday.
He said it remained to be seen whether it was a victory for the families, who had been let down so many times before.
Ninety-six Liverpool fans died in the tragedy in April 1989.
'Significant change'
Ninety-five supporters were killed in a crush of fans at Sheffield Wednesday's ground, where the club was playing an FA Cup semi-final against Nottingham Forest.
The 96th victim was in a coma for three years and died in 1992.
Trevor Hicks, the president of the Hillsborough Family Support Group, who lost two daughters at the match, said on Tuesday he welcomed the vote but admitted it could be some time before the findings were released.
He said: "The report from the independent panel will be published probably in May or June of next year but again, our position on that is we want them to do a full and proper job, and we would rather them take a few more months and do the job properly than rush it and meet an artificial timeline."
The debate was triggered by 140,000 people signing an e-petition, set up by Liverpool fan Brian Irvine.
He said: "I hope in the end the family get the answers that they are looking for from this.
"They are the most important people at the end of the day. I hope Theresa May will be good to her word and all the relevant documents will be released to the relevant panel and they can get closure on this after 22 years."
Liverpool Riverside MP Louise Ellman, who took part in the Commons debate, said it was a significant step forward.
She said: "Lost lives cannot be regained but bereaved families have just waited too long to find out just what happened.
"This means that all the papers the government holds will be released so I think that is a very significant change."
Mr Rotheram, whose Walton constituency includes Anfield, opened the debate on Monday.
He said there had been a campaign to blame Liverpool fans for the tragedy and has called on the prime minister to issue a formal apology.
The MP is also making a fresh demand for an apology from The Sun newspaper over its infamous "The Truth" headline and story which alleged drunken and criminal behaviour by Liverpool fans.
Labour frontbencher Andy Burnham has also welcomed the disclosure, saying it was one of the "biggest injustices of the 20th Century".
He said: "The home secretary has made an unequivocal commitment to full disclosure, echoing the words of the Prime Minister in his letter to me.
"We thank her for it. And the fact that there is now agreement across this house between all parties shows the watching world that this is not about party politics but the fundamental rights of victims and their families."
He has joined Mr Rotheram in calling for an apology from the government.
Speaking to Radio Merseyside on Tuesday, he said: "Some people are confused as to why a prime minister who obviously wasn't there 22 years ago would be forced to make an apology but he apologised after the Saville Report for the atrocities on Bloody Sunday.
"I think it is appropriate that if, as we all believe, the government was complicit in any of this cover up, then the prime minister now should apologise for the government's mishandling of what happened at Hillsborough."