The station, which is attached to the Manchester Arena where Salman Abedi wrought death and destruction on the city, was shut to allow a forensic search of the area to take place.
Twenty-two people were killed and dozens injured after the bomber struck following a concert by American singer Ariana Grande.
Greater Manchester mayor Andy Burnham and Transport Secretary Chris Grayling were among those to lay wreaths at the station on Tuesday morning.
Speaking to the Press Association, Mr Burnham said: "The response has been truly phenomenal from everybody.
"We've seen the best of our people, the best of our public services, the whole place has pulled together and helped everybody through what has been our darkest week.
"You do see the best of people at moments like this and I think that gives us all something to cling on to in what is a very difficult time and remains so.
He added: "What's been extraordinary for me is to see the true character of the place and the people at its most intense way and it's made me so proud actually.
"I want to capture this spirit we have had in the city, this togetherness, and use that to pull communities together to then do a better job of tackling extremism."
Meanwhile, hundreds of mourners paid an emotional tribute to the victims of the Manchester terror attack on Monday night, exactly a week after the attack.
People of all ages stood alongside each other in quiet contemplation shortly after 10.30pm at St Ann's Square, the site that has become the unofficial memorial site for those killed and injured in the blast.
The vigil, illuminated by the gentle light from hundreds of tea candles, was a moment of quiet reflection for a city united in grief.