Under the new partnership between the two US-based organisations, CrowdRise, which will keep its brand identity, will focus on fundraising for charities while GoFundMe concentrates on fundraising for individuals.
The merger follows the announcement earlier this month that GoFundMe had appointed its first UK representative as part of its efforts to expand into Europe.
GoFundMe says it is the world’s largest social fundraising platform and has raised more than $3bn (£2.5bn) for charities since its launch in 2010 through more than two million campaigns worldwide.
Founded the same year by a group of people including the actor Edward Norton, CrowdRise has a million members and 20,000 charities on its platform. Its campaigns have raised more than $500m (£409m) for non-profit organisations.
Rob Solomon, chief executive of GoFundMe, said the acquisition came about because there was a "perfect synergy" between the two companies.
"GoFundMe aims to be the giving layer of the internet," he said. "By joining forces with CrowdRise, we can offer both people and organisations the right fundraising strategy for any sort of cause they care passionately about."
Norton said: "We share the same conviction that there needs to be a platform specific to people’s passion to support causes just as much as there are platforms for their social lives, their business lives and anything else. GoFundMe has built one of the most powerful tools for social good ever and we are so psyched to join forces with them."