The Most Rev Justin Welby has assumed the position at Charis Tiwala, an organisation he has had links with for almost two years.
He said: "If you want to see the kind of things Jesus Christ is doing in the world, take notice of Charis. If you want to experience the hope this Jesus Christ brings, meet the women of Charis."
Charis Tiwala keyworkers and volunteers visit places such as saunas, offering to women they meet chaplaincy, befriending support and an opportunity to leave behind their lives in the sex industry.
Delighted to become patron of @CharisTiwala . An amazing example of love for Jesus & the transformation He brings https://t.co/kai19PMr8m pic.twitter.com/4neavBB1ng
— Justin Welby ن (@JustinWelby) August 10, 2017
They provide the women with activities including baking course, Bible studies and pilates classes, as well as assistance with sexual health.
Archbishop Justin added: "If you want to weigh up the cost of serving in Jesus Christ's name, consider the faith of the women who began Charis.
"If you want to show your love for Jesus Christ and the transformation he brings, support his work through the ministry of Charis."
Charis Tiwala said: "It's an honour to have Archbishop Justin as a patron of Charis.
"We hope it will encourage church leaders to engage with some of the issues that women who are sex workers face, and to advocate for them.
"Women in the sex industry often feel isolated, unseen and unvalued, our hope is that this will give them a sense of being seen and valued."
The founder and director of Charis, who can't be named for safeguarding reasons, said: " We want the women to know Jesus loves them, and can change their lives too if they want that.
"Some of the women have been very open to faith and God. It's been an incredible journey for us as a team. We have seen some of the women leave the industry and get new jobs. Some have become Christians.
"The other side is that we've seen women being horrifically exploited, and one woman who was murdered. But it is a privilege to do this work and see the difference that God can make in people's lives."