The ceremony, hosted by Jason Derulo and Alesha Dixon at Glasgow's SECC, also saw Adele and Rihanna win an award each.
The 23-year-old 'Price Tag' singer won four of the five awards she was nominated for, including 'Best UK Act' and 'Best Newcomer'.
She also won 'Best Album' for Who You Are and 'Best Song' for 'Do It Like a Dude'.
Adele won the award for 'Best R&B/Soul Act', while Rihanna was voted the 'Best International Act'. Tinchy Stryder and Dappy shared the award for 'Best Video' for their duet 'Spaceship'.
Tinie Tempah was named 'Best Hip-Hop/Grime Act', while Wretch 32 missed out on the four awards he was up for.
Boyz II Men performed a medley of hits at the ceremony, as well as collecting the 'Outstanding Contribution to Music Award' from JLS.
Amy Winehouse was given a special tribute during the ceremony, which was introduced by her god-daughter Dionne Bromfield.
Kanya King, the CEO and Founder of MOBO, said: "The excitement and atmosphere of our second year here in Glasgow has shown the love that the whole country has for MOBO. We felt so welcome the first time we came here, we didn't think it could be topped.
"This year has been a phenomenal success and we can't wait to return in 2013. It's been a great event that has welcomed some exciting new award winners to the MOBO roll of honour including the global superstar Adele, the UK's hot talent Tinchy Stryder and of course the fantastic Jessie J walking away with four awards."
Jessie J was named as the first judge on BBC One's UK version of The Voice earlier this week.
> Read the full list of winners from the MOBO Awards 2011 here
Watch the video for Jessie J's 'Who's Laughing Now' below: