The brave schoolgirl was born with arthrogryposis, a rare condition which means her joints fused in position so she can't bend her limbs or fingers.
Medics in the UK said she would never walk and would be wheelchair-bound for life as her condition was so severe - but doctors in the U.S believed there was hope.
Her parents hoped to be able to take her abroad but the costs were $125,000.
But generous donors gifted £50,000 to pay for it, in addition to another £30,000 raised.
Dad-of-two William Green, 36, said the schoolgirl's achievements were proof 'the tide could turn' at any time, after she took her first steps following an op in Poland.
Arabella is taking between 50 to 100 steps per day and is only awake for two hours, due to the physical effort of learning to walk.
Tragically, her mum Catherine Wood, 27, took her own life in March 2021 after an uphill struggle to get treatment for her severely disabled daughter.
Arabella flew to Poland with dad William, who works as an electrician, on October 17, and stood up for the first time on December 16, taking a few steps with the help of a physiotherapist.
She took her first steps alone at the Paley European Institute in Warsaw on January 8, using a walker, and was able to walk to ring a bell on January 14 - the day they flew home.
William, from Bathgate, said: "She's doing great, she's only been awake for about two hours a day.
"She's not walked for six years.
"She's not got any quadriceps in her legs, so she is wearing knee, ankle, foot and forceps supports to support her legs.
"If Arabella had this done two or three years ago she wouldn't be going through so much pain.
"It had to be done before she was six.
"Her mum Catherine begged the doctors before she died but they said it was impossible."
Arabella uses a crocodile walker for getting around and has an electric wheelchair.
She is coming on leaps and bounds at school despite the setbacks she has experienced.
Only 15 per cent of her leg muscles work, and she has had metal rods inserted into her bones which her dad described as 'like pencils'.
William said: "We are working on building her confidence.
"The main thing is since having the op she's been able to stand on her feet.
"Arabella is the first child in the world to walk without quadriceps muscles, she was also born with no biceps.
"She walks by using her glutes and abdominal muscles.
"The condition she has is very rare, we've not come across anyone else who has it in Scotland.
"She's doing brilliantly at school, because the brain is the most important muscle in her body.
"The op was such a success, seeing her standing and walking has been amazing.
"We are so grateful to the people who have helped us get here, she's inspired children all around the world."