The welcoming sentiments were given as the Northern Ireland Order, which will implement devolution and transfer powers from Westminster to the new Assembly, cleared Parliament.
Speaking during debate in the Lords, the former Tory secretary of state Lord Mayhew of Twysden said the risks involved were "manageable and justified. There have been times, and no doubt long periods of time, when that elusive objective [of ending direct rule] seemed very remote indeed.
"But now we have an agreement which represents not so much a step as an enormous leap towards that objective. It is a leap which has saved the people of Northern Ireland, for a short time at least and in any event, from a poisonous political stalemate and it offers them an enormous opportunity."
Lord Merlyn-Rees, a Labour former Northern Ireland secretary, added: "There are problems ahead, but this is a great day for Northern Ireland. We must all do our best to help in every possible way."
Lord Laird, a crossbencher who lives in Ulster, praised the "very difficult and courageous decision of David Trimble and his official Unionist party.
"I have been a member of that party for 35 years. I have witnessed sights that I would not wish to describe to anyone here. I have lost colleagues and relations, friends and next-door neighbours in tragic circumstances - yet I think it is to the great credit of my party and inspirational leadership of David Trimble that we have got to this position."
Earlier, the Northern Ireland minister Lord Dubs said the measure represented "the triumph of normal democratic politics over violence. Let's give it a chance. This Order, although one of the shorter pieces of legislation I have brought to the House, marks one of the most significant of all these. It represents the triumph of normal democratic politics over violence as a means of accommodating different traditions and viewpoints in Northern Ireland."
Lord Dubs said that although there was scepticism about the decommissioning of weapons by paramilitary groups, and concern about what the Government would do if it did not happen, he believed it would take place.
Lord Glentoran, a Tory hereditary peer who lives in Antrim, welcomed the Order as "historic". But, he warned: "A word of caution. The terrorist threat has not yet gone away. Organised crime flourishes with the various paramilitaries. A high level of policing and vigilance must remain in the province and in the mainland despite the political problems this may create."
Lord Goodhart, for the Liberal Democrats, said it was an occasion for "relief that the peace process had survived its voyage".
In a reference to the appointment of Sinn Fein's Martin McGuinness as Minister for Education, Lord Goodhart asked for "checks and balances" to allay people's fears about actions by ministers representing parties whose views were highly controversial.