'Sing' sold 142,000 copies to claim 2012's biggest-selling weekly number one, beating DJ Fresh's 'Hot Right Now' which sold 128,000 to reach number one in February.
Barlow said of his first number one away from Take That since 1997: "It's been such a great week, it would take something very special to top it. I'd like to say thanks on behalf of about 200 people as we've got a massive cast on this record.
"I love collaborating with other artists and being able to put them all on one stage the other night was such an honour for me. It's something I'll never forget."
'Sing' also outsold the rest of this week's top three combined, while also achieving a chart double for Barlow, who is also number one in the UK album chart.
Flo Rida's latest single 'Whistle' lands in the runner-up spot, despite only being released halfway through the past week. fun. fall one spot to three with 'We Are Young'.
Rudimental's 'Feel the Love' falls three places from last week's number one to four, while Usher's latest single 'Scream' lands at five.