The appeal, launched on a donations website, received more than 2,000 contributions within three days.
Bracknell, who played Zoe Tate in the ITV series from 1989 to 2005, set up the campaign for treatment in Germany.
The 52-year-old mother-of-two has been working as a yoga instructor in recent years.
Her character in the soap was known for storylines which raised awareness about mental health and LGBT issues.
Bracknell, whose real name is Alison and is known to her family as Ali, only discovered she was battling terminal lung cancer five weeks ago.
She and her partner Jez Hughes wrote about the news and their hopes to save her life on the fundraising page.
They explained that doctors said the cancer was "terminal, not curable, not operable" but their research led them to want to try a new treatment being used in Germany.
Mr Hughes wrote: "The downside is that these cutting edge treatments aren't yet available on the NHS outside of clinical trials and are very expensive... This is why we are fundraising here."

Bent rescued a point for the Rams against Sheffield Wednesday, heading in the equaliser a minute after coming off the bench on Saturday.
Derby, already assured of a play-off spot, are unbeaten in five games.
"The main thing is that we go into the play-offs full of confidence and not losing games," Bent said.
Former England striker Bent said falling at the first hurdle of the play-offs against West Ham in his last season with Ipswich Town in 2004-05 was a harsh early lesson in his career.
"A fair few years ago now at Ipswich, our season had gone because we only managed to win one out of our last five games. We went into the play-offs with no real confidence," Bent told BBC Radio Derby.
As for his own personal form, Bent was pleased to make an impact as a substitute having not featured since Derby's 3-3 draw with Rotherham in March.
The goal was the former Aston Villa, Sunderland and Charlton forward's first since netting the winner in Derby's 2-1 FA Cup third-round win against League Two side Hartlepool in January and only his second in the Championship this season.
Bent scored 12 goals in 17 games during a loan spell at the iPro Stadium from Villa last season, before signing a full-time deal last summer.
"The boys have been joking it was my first touch in three months, it was nice," Bent said.
"It was a while for that one to come. It's been difficult to get minutes on the pitch with the team playing really well, Chris Martin at the top of his game and the two wide men playing well.
"To be match sharp is impossible if you play a few minutes every four or five weeks, but when you do get on the pitch you want to help the team out, and it worked."

The plant was connected to the grid on Tuesday, Press Trust of India reported.
In May, India's Supreme Court ruled that the power station could start operations as it was "safe and secure".
Opponents of the plant, which is on the coastline hit by the 2004 Asian tsunami, fear a disaster similar to the one at Fukushima in Japan in 2011.
Last year, Kudankalum was the scene of mass protests over safety concerns.
But the government says the joint Indo-Russian project, which is seen as critical to India's energy needs, is "necessary for the welfare and economic growth of India" and is "completely safe".
The plant is one of many that India hopes to build as part of its aim of generating 63,000 MW of nuclear power by 2032 - an almost 14-fold increase on current levels.
The plant became operational during Prime Minister Manmohan Singh's two-day visit to Moscow.
Mr Singh was expected to finalise a deal with Russia for more reactors for the plant, but it fell through as Russia has refused to sign India's nuclear liability law.
The law stipulates that nuclear firms aiming to set up plants in India will have to pay huge sums of money in case of an accident and Delhi and Moscow have not been able to agree on this clause.
A campaign to raise £50,000 for former Emmerdale actress Leah Bracknell to undergo lung cancer treatment has reached its target.
[NEXT_CONCEPT]
Striker Darren Bent was relieved to score with his first touch in six weeks to keep Derby County's unbeaten run intact ahead of the play-offs.
[NEXT_CONCEPT]
The controversial Kudankulam nuclear plant in India's Tamil Nadu state has begun producing electricity after years of delays and protests, officials say.