But it is unclear how many of the 250-odd advertisers have returned to YouTube and other parts of the Google Display Network.
A report by ABC News said that big US telcos Verizon and AT&T were still staying away from Google.
The boycott began in March after the London newspaper The Times reported that advertisements for the government and major brands were appearing next to content that pushed extremist, racist and anti-Semitic material.
In Australia, the federal government, Tourism Australia, Vodafone Australia, Nestle, Bunnings, Foxtel and Caltex joined the boycott.
ABC quoted Harry Kargman, who runs Kargo, a company that helps manage ad campaigns on mobile devices, as saying, ""This is an ostrich situation where the ostrich just pulled its head out of the sand."
He said that even if advertisers returned, they would cut down on their spending. "It's going to be a slow burn as brands quietly shift their spending away. There are now questions about the quality of video on YouTube in the long term."
iTWire has contacted Google and asked the company how many companies that pulled their ads have now returned.
The ABC report quoted Mark Mahaney, an analyst from RBC Capital Markets, as saying YouTube and Google's ad network for video on third-party sites could lose US$300 million, to US$1.5 billion this year.
He said some of the reduced spending could shift to Facebook.