Embattled world champion Armitstead was given a Rio reprieve over three whereabouts ‘failures’ when the first was declared void by the Court of Abritration for Sport.
But Britain’s first medallist of London 2012, with silver on The Mall behind Marianne Vos, could only finish fifth in the 137-kilometres road race as Holland’s Anna van der Breggen won a dramatic gold.
Armitstead said: “I can’t feel sorry for myself. This is sport and that’s what it’s about.
“You open yourself up for judgement. I never gave up and for that I can be proud of myself.
“Obviously I’ve lost quite a lot of sleep and it’s been a hard time, but it’s not an excuse.
“Once I’ve got a number on my back I’m a totally different person and I’m focused and it didn’t enter my mind once in the race. I was totally focused on what I do best.
“It’s a deserving Olympic champion for sure.”
Holland’s Annemiek van Vleuten led with less than 11km to go, but crashed dramatically on the descent which had ended men’s road race leader Vincenzo Nibali’s chances 24 hours earlier.
Initial reports on Twitter from the Dutch Cycling Federation said Van Vleuten was “okay”.
The crash allowed Mara Abbott of the United States to take the lead, with Sweden’s Emma Johansson, Elisa Longo Borghini of Italy and Van der Breggen Holland in pursuit.
Abbott had an advantage of almost 40 seconds as the descent flattened out, but was caught in the final 200m and denied a medal.
Van der Breggen took gold, Johnsson silver and Longo Borghini bronze.
Armitstead added: “It wasn’t entirely unexpected. I knew I was going to need a miracle to come away with the gold medal on this course.
“I’m really happy with the tactic that I had and the effort that I did. I came up short on the climb. That’s what I’ve been working hard on, but that’s sport.”
It was a compelling race, but Chris Boardman, 1992 Olympic champion and BBC co-commentator, thought the route was “dangerous”.
He told the BBC: “I’m really just waiting for news on Van Vleuten; it’s very hard to concentrate when you see a crash like that.
“I’m actually quite angry because I looked at the road furniture and thought nobody can crash here and get up. This was way past technical, this was dangerous.”
Armitstead – after being escorted by team officials to sign on for the start alongside her team-mates Emma Pooley and Nikki Harris, neither of whom finished – was cheered by a small throng of supporters waving Union Flags with “Team Armitstead” inscribed upon them and a banner on which “Go Lizzie” was written.
The 27-year-old from Otley had her sunglasses on her helmet and a steeliness about her eyes on her arrival at the start after a trying week.
Armitstead had been provisionally suspended by UK Anti-Doping on July 11 for three whereabouts ‘failures’.
CAS ruled in her favour, scrubbing the first ‘strike’ from her record, but her results will forever have an asterisk alongside them in the eyes of many who believe she should not have been in Rio at all and should instead be serving a two-year suspension.
Questions remain, but Armitstead was unable to fan the flames of controversy by winning a medal.
Armitstead, who said she was looking forward to now spending time with her friends and family, added: “I have to come to terms with it. I can’t pick up the phone to everybody that doubts me and explain myself.
“The only thing that I can do – and the only thing that I’ve always done – is to ride my bike fast and get my head down and control the things I can control.
“I’d be lying if I said I wasn’t looking forward to putting this behind me, but it’s the Olympic Games and at the end of the day I’m a sports fan.
“I think Team GB are going to have some extraordinary performances and I hope that the nation doesn’t lose faith and they get behind the team because it’s going to be a good two weeks of sport.”
Armitstead added she had support from her fellow riders within the peloton. Her race began with an early puncture, but she swiftly returned to the bunch, which was going at a frenetic pace.
A seven-rider group, which included Vos, saw their advantage of more than one minute soon evaporate on the slopes of the Vista Chinesa.
After Van Vleuten’s crash, Abbott broke alone but was caught by the three-strong chase group in the last kilometre. Armitstead sprinted to the line to take fifth ahead of the rest of her chase group.