With his mother, Victoria, he will fly to Galeao International Airport and spend four nights in Rio, with accommodation, meals and group activities included.
"This is a dream come true for Will," Mrs Richardson said.
"He lives and breathes football and is so excited about meeting an international pro-footballer and walking them on to the pitch. This will be an experience he will never forget; nor will I."
Will won the prize by completing football challenges at a McDonald's Skills Zone Day event this month.
The competition was open to 6-10-year-olds and attracted more than 1000 entries.
NZ Football chief executive Andy Martin said: "Congratulations to Will for winning this amazing prize. We'd like to thank all the children who took part in the Skills Zone Day events and entered the competition. It was great to see such enthusiasm from so many young football fans."
Three Skills Zone Day events were held in Auckland, Wellington and Christchurch. Children who were unable to get to one were able to enter online by uploading a video of their skills.