The city dedicated a permanent 9/11 Memorial and Memorial Garden, which includes a steel I-beam from the World Trade Center's north tower.
Moments of silence were held at 8:46 a.m., 9:02 a.m, 9:37 a.m. and 10:03 a.m. marking the times when the four hijacked airliners crashed into the two World Trade Center towers, the Pentagon and a field in Pennsylvania.
Of the nearly 3,000 people killed, 161 had ties to Connecticut.
Malloy paid tribute to them and the first responders who perished in the attack.
"There is something special about people who would do this work," he said. "In remembering their duty, in remembering their sacrifice, let us not forget that each and every one of them was a person of great potential, who was loved and embraced by their family."
Mary Canty of Durham, whose brother Michael perished in the attacks, also spoke at the ceremony, one of several held around the state.
The official state observation of the Sept. 11 anniversary Tuesday drew participants to Sherwood Island in Westport, where a memorial that includes stones engraved with the names of the Connecticut victims stands across Long Island Sound from lower Manhattan.
"It's important that people stop and just take a minute to remember," Canty said.