In the Islamic centre, blood smeared the floor and walls and bullet holes could still be seen in the aftermath of the carnage.
Worshippers said they wanted to show the world the scene of the crime.
Alleged gunman Alexandre Bissonette, 27, has been charged with six counts of murder and five of attempted murder.
Mosque vice-president Mohamed Labidi, in an emotional news conference, said they were opening the mosque to show the consequences of hate and Islamophobia.
He said they had been "attacked in the heart of their community".
Mr Labadi also described the courage of one of the victims, Azzedine Soufiane, 57, who died trying to protect other worshippers as the gunman entered the mosque on Sunday during evening prayers.
"When he saw the attacker recharge his gun, he ran quickly to immobilise him," said Mr Labadi.
"But the attacker was quicker and shot him directly and he fell down here, he fell down here as a hero." He pointed to a patch of blood on the floor.
"Without his intervention, we would have more martyrs."
Mr Soufiane ran a halal butcher shop in the suburb of Sainte-Foy, down the street from the Quebec Islamic Cultural Centre, and has been described as an important member of the local Muslim community.
The six worshippers who died were immigrants who had moved to Quebec to seek a better life.
The other victims were Khaled Belkacemi, 60, Abdelkrim Hassane, 41, Mamadou Tanou Barry, 42,  Ibrahima Barry, 39, and Aboubaker Thabti, 44.
The funerals for three, Mr Hassane, Mr Thabti and Mr Belkacemi, will be held in Montreal on Thursday and their bodies will be repatriated to their countries of origin.
In the wake of the deadly shooting, Quebecers and their political leaders rallied around the province's Muslim community, with thousands attending vigils to commemorate those killed and injured.

The experiment will begin when the first round takes place on Saturday 24 September.
It is an initiative being introduced by the Scottish FA after recent talks with the International Football Association Board.
Previously, teams could only use three of seven substitutes in Scotland's premier cup competition.
The fourth replacement will only be available if a tie is level after 90 minutes and goes to extra time.
There are no plans for the format to be introduced by the Scottish Professional Football League, but it could be used in next season's League Cup in Scotland.
The SFA announced the extra substitute plan as Hibernian captain David Gray made the first-round draw at Edinburgh College.
One preliminary-round tie remains to be played without the availability of an extra substitute after Scottish Junior Cup winners Beith Juniors and West Superleague champions Auchinleck Talbot drew 2-2 at Bellsdale Park on Saturday.
Talbot host their West Superleague rivals this coming Saturday with Highland League outfit Strathspey Thistle now preparing for a journey south to face the victors.
East Superleague champions Bonnyrigg Rose and North Superleague champions Banks O'Dee both face a trip to the Highlands to face Turriff United and Keith respectively.
East of Scotland champions Leith Athletic host Cumbernauld Colts, who finished fourth in last season's Lowland League.
Beith Juniors or Auchinleck Talbot v Strathspey Thistle
BSC Glasgow v Rothes
Civil Service Strollers v Hawick Royal Albert
Clachnacuddin v University of Stirling
Dalbeattie Star v Wick Academy
Deveronvale v Gretna 2008
East Kilbride v Vale of Leithen
Edinburgh University v Whitehill Welfare
Forres Mechanics v Lossiemouth
Fort William v Brora Rangers
Gala Fairydean Rovers v Fraserburgh
Girvan v Huntly
Inverurie Loco Works v Buckie Thistle
Keith v Bank's O'Dee
Leith Athletic v Cumbernauld Colts
Nairn County v Preston Athletic
Selkirk v Linlithgow Rose
Turriff United v Bonnyrigg Rose
Ties will be played on Saturday 24 September.
The Quebec City mosque that was the scene of a deadly shooting on Sunday has opened its doors for the first the since the attack.
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A fourth substitute will be available in extra time for the first time in this season's Scottish Cup.