Boston bombing survivor has run her first marathon since losing her leg.

Images: Rebekah Gregory before and after the marathon (Facebook).

Two years ago, Rebekah Gregory was standing near the finish line of the annual Boston Marathon when two homemade bombs went off on the sidewalk.

Three people were killed in the blast, and more than 260 runners and spectators were injured. Gregory was left fighting for her life, and became one of 16 survivors to lose a limb in the aftermath — after undergoing 18 surgeries, the mum of one had her left leg amputated in November last year.

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Yesterday, Gregory was back at the finish line of the Boston Marathon; only this time she was crossing it with the help of ‘Felicia’ and ‘Forrest’, her new prosthetic leg and running blade.

In 2014 she competed in a tribute run of the same route in her wheelchair, but yesterday she ran the last 3.5 miles (roughly 5.6km) of the marathon, accompanied by a trainer and fellow amputee.

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"Just to know that I was crossing the finish line on my own foot and I wasn't in a wheelchair like last year and I wasn't laying on the pavement fighting for my life like the year before," she told ABC News. "I've come a long way and I'm just going to keep going because there's no stopping me."

Gregory's achievement comes just weeks after she testified in the trial of convicted Boston marathon bomber Dzokhar Tsarnaev. The sentencing phase of Tsarnaev's trial begins tomorrow; he faces life imprisonment or the death sentence. (Post continues after gallery.)

"It is extremely emotional to look back on the last two years of my life. To remember what it felt like to be bleeding out on the pavement, wondering if I would ever see my child's smile again. In a matter of minutes, my entire world changed. Everything I knew was literally blown to pieces, and I was forced to start picking them up one by one," Gregory wrote in a Facebook post last week, which has since received thousands of likes.

"A few days from now I will be going back to that same pavement on Boylston Street... This time I won't be laying on the ground in pieces, or having to be assisted because I can't do things on my own. This time, the only thing hitting the ground will be my running shoe, as I show myself and the rest of the world that I am back, stronger than ever, and there is NO stopping me now."

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Over the past two years, Gregory has been sharing her journey with the thousands of people who follow her on Instagram, Facebook and Twitter. In the lead-up to her amputation last year, Gregory posted a 'breakup letter' to her leg, writing: "Go get yourself one last pedicure on me and enjoy it because tomorrow... I will be cutting you out of my life for good."

Since 'Felicia' was fitted, Gregory has kept her followers updated on her training progress. Last month she wrote, "I'm a long way from where I want to be... but I'm also a long way from where I was. Don't ever give up because I am living proof that what doesn't kill you DOES make you stronger."