Brabants, a former World and European sprint champion who was awarded an MBE in 2009, was part of Team GB atLondon 2012 but finished last in the K1 1000m final and suggested then his competitive career may have been close to the end.
He kept his options open by taking part in the national selection events in Nottingham at the weekend and succeeded in making the eligibility criteria.
Brabants could, therefore, have continued to represent his country this year but instead opted to bow out.
"This has been an incredibly difficult decision to make, but reluctantly I realise I have reached the point where I need to retire from the sport," said Brabants, who will now pursue a career in medicine.
"It has become more obvious to me over the last few months that as much as I love the sport and would love to be Olympic and World Champion again, I've reached the point where I'm unlikely to improve or achieve the same results that I once achieved.
"It is a difficult decision and it is not based on this weekend, because I have done well enough to be selected to race internationally from my results.
"But it wouldn't be right to just keep competing for the sake of competing and, when you're not getting your best results, it wouldn't be fair on my family or on the other athletes in the sport that are trying to come through."
Phil O'Hare, Piccadilly line manager for London Underground, said:
"The RMT's intention to ballot is completely unnecessary.
"The union has raised a number of unrelated local issues with us around the application of current LU attendance and disciplinary procedures, all of which we addressed and explained through several meetings with union representatives three months ago.
"In addition, discussions are ongoing through the processes agreed with all unions about the nature of working facilities at the Northfields depot due to open shortly. All of the union's issues have either been addressed, or are being, and I would urge them to continue to discuss any matters which they feel have not been dealt with, in the normal way."
Tim Brabants will defend his Olympic title in the final of the men's canoe sprint. There were roars of encouragement from the crowd at Eton Dorney when the 35 year old qualified for the men's 1000 metres K1 final by just four hundredths of a second.
Brabants, who’s from Walton-on-Thames, Surrey, said the cheering spectators pushed him through the last 100 metres of the race.
"You heard a lot of other athletes talking about it last week, about how the crowd pushes you on, but until I was out there doing it I didn't appreciate the impact ithas."
Brabants has spent the past 18 months battling to recover from a tendon injury, and admitted the final this week will be tough.
"It hasn't been easy and these guys are performing exceptionally well at the minute and it is going to take a really special thing for me to just to make it on the podium on Wednesday.
"But I feel in good shape and I am hoping for a good result."
Later this month, the British canoe sprint squad will be heading to a competition in Poland, which for some of them will be a chance to book their places in the Olympic team. Amongst them is Olympic gold medallist Tim Brabants. But his place in the team is under threat. Phil Bayles reports.