Chloe Nash Lowe asked bosses at Sheffield's Meadowhall centre if there was anything that could be done about slow walkers holding her up when she and her family visit.
She listed the reasons why sluggish shoppers should speed up, and asked: "Will you ever tell people not to walk so slow? If you do this for me I will be delighted - please do it."
Chloe, who goes to Aughton Primary School near Sheffield, then suggested an overtaking lane for quicker customers.
Centre Director Darren Pearce thought it was a brilliant idea and members of the Meadowhall team met Chloe to discuss her suggestion and present her with a £20 gift voucher.
The mall is now trialling the over-taking lane and invited Chloe along to test out the system for herself.
Mr Pearce said: "I want to thank Chloe for taking the time to write in and share her views with us - we love to hear feedback from our younger shoppers.
"The Meadowhall team liked Chloe's idea so much that we have decided to trial an over-taking lane for fast walkers on the malls - helping them to get where they want to be on time - let's see how it goes!"
Delighted Chloe said: "When my teacher, Mr Lawson, asked me to write a letter about something I'd like to change I never thought it would actually happen.
"Thank you to the people I met at Meadowhall who gave me a voucher to spend on my next visit - I think it looks great and am so pleased to see it in action."