It was at the age of 11, sitting in his parents' front room in north-east England that Akinyemi figured out what he wanted to do with his life.
He was watching the final Olympic run of British canoeist Paul Ratcliffe at the 2000 Sydney Olympics.
By 2006 he was junior British national champion. But by this point, as many teenagers do, Akinyemi had begun to struggle with issues of identity. "I don't like to make too much of my ethnicity but I think it can be hard growing up in British society as a mixed-race lad.
Akinyemi asked his father to take him to meet other Nigerians in the local area, particularly those of the Yoruba ethnic group to which he belongs.
"The first time I went, a mixed-race lady in our local Yoruba club said to me: 'When you first fly to Africa and touch down there, you'll know it's in your blood, you'll know you've come home.'"
Akinyemi first visited Nigeria in 2007, aged 18. Within the year he had signed up for the Nigerian team.
"There's a choice, either you can ignore who you are or embrace it.
"I personally am really proud of my Nigerian nationality and want to embrace it as much as I can."
Once nationalised, Akinyemi set about exploring the lakes and river systems around Lagos, Nigeria's commercial capital.
He is convinced that Nigeria and Africa more broadly could become the geographical powerhouse of the sport.
"What we've got here in London is great, it's really great, but when you look in Africa there are all these natural white-water courses which are bigger and better than any of the man-made ones in Europe.
"And all those rivers are ready made and just waiting to be explored," he says.
Africa regularly loses many of their highly skilled athletes to more lucrative leagues overseas.
Canoeing, however, seems to be bucking the trend.
Johny AkinyemiIf I can inspire young Nigerians to rise through the ranks and beat me then that would be a really great thing”
Competing for Nigeria is important for Akinyemi.
"It felt really special to do it in reverse. For me to go back and to be accepted with open arms was truly a humble moment," he said.
"They never had to take me.
"I'm really grateful to the Nigerian Olympic Committee for allowing me to do it and for helping me explore that side of me," he added.
"If I can go there and help unlock the future of Nigerian young canoeing or in any way help to inspire young Nigerians to rise through the ranks and beat me then that would be a really great thing."