He played at the Manchester Etihad stadium, and after belting out his classic Let Me Entertain You, Robbie took to the centre of the stage to deliver a message.
He said before playing the track: "This next song is dedicated to all the people that tragically lost their lives last week here in Manchester". "Sing it for them!"
He often made attempts to fill in the words but was too tearful to do so, as seen in a Twitter video captured by BBC Sports editor Stuart Rowson and Liverpool Echo deputy executive editor David Raven.More news: Iraq paramilitary troops take strategic town west of Mosul
After being greeted by his friends at Take That, the singer opened his set with his ballad Strong, but he put an emotional and Mancunian twist on the lyrics.
Struggling to sing the verses, the crowd helped him sing the song, as tears rolled down his face.More news: Champions Trophy: India to clash with arch-rival Pakistan
Opening his show, Williams told the crowd: "We are Manchester and we are not f**king scared" before later altering the lyrics in the chorus of Strong, as seen in the video below.
The concert was the first stop on Williams' Heavy Entertainment Show Tour.
He'll be back in Manchester with Take That for the Ariana Grande benefit concert next weekend.More news: Tiger Woods blew zero for booze, but was 'droopy,' cops say
- Van Mows Down Pedestrians on London Bridge, Stabbings Reported Nearby
- Donald Trump criticises Sadiq Khan's response to London attack
- Environment minister calls US withdrawal from climate deal 'regrettable'
- NATO to be full member of global coalition against ISIS: Chief
- May condemns 'evil ideology' behind London terror attack
- Trump on Offensive as Kushner in Trouble
- Spicer Says 'Covfefe' Was An Intentional Inside Joke
- Lanka's stand-in captain Tharanga suspended for two matches
- Climate action 'unstoppable', nations should stay course: UN chief
- Trump's Press Chief Quits Amid White House Shake-up