Pupils from across the borough put their general knowledge to the test as they battled it out in the MasterMind in Harrow competition.
Six schools took part in the contest, organised by charity Mind in Harrow and sponsored by the Harrow Times.
They raised more than £6,000 for the mental health charity.
The 72 pupils, split into teams of four, were tested in maths, English, science, history, before going into a general knowledge buzzer round.
Taking part were Hatch End High School, Bentley Wood High School, Harrow School, Sacred Heart, John Lyon School and North London Collegiate School.
See a picture gallery of the competition here.
The overall winners of the competition were Harrow School's Team Brilliant.
Captain Hari Rattan, 14, said: “It’s great to win but I think the important thing for me has been raising the money for a good cause.
“We worked really hard for the quiz and made sure we revised. There was a really good atmosphere for the competition and I think everyone really enjoyed it."
The winner of the most innovative fundraising award went to the Sacred Heart Language College for their school sleepover.
Captain of Sacred Heart’s Team Brilliant Alicja Macheta said: “We’ve really enjoyed ourselves and it’s great to have won.
“We wanted to do a sleepover at the school for a while. And it was the perfect way to raise money for Mind in Harrow.”
The award for raising the most money went to North London Collegiate School, which raised more than £1,300.
Captain Amy Toledano said: “We’re really proud to have raised the most money and the whole competition was really fun. We’re glad we were able to do out bit to support a really good cause.”
The competition took place at Harrow School throughout the afternoon.
Each school entered three teams of four, and for the past five months each team has had the fundraising challenge of collecting £400 for the charity as entry into the competition.
At the event it was announced all the schools had raised more than £6,000 for the charity, with more possibly still to come.
Chief executive of Mind in Harrow Mark Gillham said: “All the teams have done fantastically well and it has been an amazing competition.
“It's refreshing to see all these young people have really engaged with this whole contest and I hope they have learnt a lot about mental health.
“Support from the community and schools in competitions like this are the only way charities like Mind in Harrow can carry on its work helping people in need.”
Quizmaster and Chaplain of Harrow School Father James Power said: “I want to thank all the pupils for their hard work and giving up their time when it is a very busy period in their lives.
“I think everyone who took part in the competition got a great deal out of it. The event went amazingly well and I am delighted it has been such a success.”