The 38-year-old broadcaster wore the armband in support of LGBT+ rights while fronting coverage of England's opening match against Iran, alongside co-presenter Kelly Somers.
Speaking at an event for Attitude magazine in London — reported via the Mirror — she admitted she "hadn't processed the magnitude" of her decision until she'd had time to reflect.
The topic of LGBT+ rights was a hot one during the tournament in Qatar, where homosexuality is illegal.
She said: "There I am in Qatar on the opening show. We spoke a lot about the politics and everything surrounding it and it was heavy.
"I remember coming off that show and being like, I don't know if I'm going to get through a month of this. The abuse, the trolling and everything had started."
Scott recounted that she had awoken the next day to the news that England and other major nations had decided not to wear the 'One Love' armband after being threatened with yellow cards.
The retired footballer, who has not labelled her sexuality but has dated both men and women, said she was motivated to take action of her own.
She said: "I was standing with the kit man, Andy, looking out, just full of emotion. I said: 'Andy, no one's told me I can't wear an armband' and he said: 'Alex, you f***ing genius'."
Scott, who played 140 times for England, added: "I remember saying to Kelly [Somers], who was going to interview me: 'Kelly don't say a word. I'm going to put this armband on and it's going to speak for itself'."
Prior to jetting off to Qatar, Scott was one of several presenters and pundits who defended the decision to cover the tournament in the wake of serious concerns about the host nation.
She said: "I love my job and when I think about it sitting here and having the harder conversations and it's bigger isn't it? We're talking about migrant workers, we're talking about the LGBT+ community, we're talking about women's rights."
Watch: Alex Scott defends covering the World Cup