Future Organics will use simple designs to reflect the brand and comprises denim clothing and T-shirts made from organic cotton.
The line will be trialled in its top 12 stores from April and follows similar launches over the past month from Topshop and Marks & Spencer.
Oasis design director Nadia Jones said one of the reasons the retailer has produced the range was it realised there had been a shift in consumer demand for ethically produced clothing.
A spokeswomen for the retailer said there were no plans to produce a promotional campaign for the brand but it would consider doing so if the trial proved successful; the Future Organics range will instead be promoted in-store.
The introduction of the collection follows M&S' recent launch of its 'Look behind the label' campaign, supporting its own Fairtrade clothing range. The drive comprised press ads and point-of-sale activity, using headlines such as 'It's not just our green dyes that won't harm the environment.'
The M&S range, launched at the beginning of January, is sold in 420 stores and was the first of its kind in the UK.
The launch followed research from online company YouGov, which showed that ethical and health issues are increasingly determining what consumers buy.