Most of the top 40 global technology companies assessed in the study by KnowTheChain, an online resource for business, had made progress since the last report was published in 2016. But the study found there was still room for improvement.
"The sector needs to advance their efforts further down the supply chain in order to truly protect vulnerable workers," said Kilian Moote, project director of KnowTheChain, in a statement.
Intel, HP, and Apple scored the highest on the list, which looked at factors including purchasing practices, monitoring and auditing processes. China-based BOE Technology Group and Taiwan's Largan Precision came bottom.
Workers who make the components used by technology companies are often migrants vulnerable to exploitative working conditions, the report said.
About 25 million people globally were estimated to be trapped in forced labour in 2016, according to the International Labour Organisation and rights group Walk Free Foundation.
Labourers in technology companies' supply chains are sometimes charged high recruitment fees to get jobs, trapped in debt servitude, or deprived of their passports or other documents, the report said.
It highlighted a failure to give workers a voice through grievance mechanisms and tackle exploitative recruiting practices as the main areas of concern across the sector.
In recent years modern slavery has increasingly come under the global spotlight, putting ever greater regulatory and consumer pressure on firms to ensure their supply chains are free of forced labour, child labour and other forms of slavery.
From cosmetics and clothes to shrimp and smartphones, supply chains are often complex with multiple layers across various countries - whether in sourcing the raw materials or creating the final product - making it hard to identify exploitation.
Overall, large technology companies fared better than smaller ones, suggesting a strong link between size and capacity to take action, the report said. Amazon, which ranked 20th, was a notable exception, it said.
"Top-ranking brands... are listening to workers in their supply chains and weeding out unscrupulous recruitment processes," Phil Bloomer, head of the Business & Human Rights Resource Centre, told the Thomson Reuters Foundation.
A spokesman for Amazon said the report drew from old and incomplete information and failed to take into account recently launched anti-slavery commitments and initiatives.
HP said it regularly assessed its supply chain to identify and address any concerns and risks of exploitation.
"We strive to ensure that workers in our supply chain have fair treatment, safe working conditions, and freely chosen employment," said Annukka Dickens, HP's director for human rights and supply chain responsibility.
Intel, Apple, BOE Technology and Largan Precision did not immediately respond to requests for comment.