Rt Rev Jonathan Clark and Rt Rev Dr Michael Ipgrave told ministers allowing Florence and Opelo Kgari to stay would mark "a step towards a more humane immigration system based on our shared Christian values of fairness and decency."
The two women, who have lived in the United Kingdom for 14 years, have faced repeated deportation attempts and have been detained at the Yarl's Wood Immigration Removal Centre since January 2018.
Opelo (pictured), 27, helped lead a hunger strike at the site in Bedfordshire for much of last month in order to highlight the treatment of detainees.
In their letter, which was printed in the Guardian newspaper on Tuesday, Bishop Jonathan and Dr Michael said: "We are concerned that the injustices that prompted last month's hunger strike at Yarl's Wood immigration removal centre continue.
"People there are calling for an amnesty for those who have lived in the UK for more than ten years and an end to the detention of those who came to the UK as children.
"We hope that immigration minister Caroline Nokes will intervene in the case of Opelo and Florence Kgari - a mother and daughter who have lived in the UK 14 years..."
The letter was also signed by Paul Barker from Quakers in Britain and Ali Johnson, an associate pastor at Swan Bank Methodist Church near Southampton.
Last week, the Independent quoted a Home Office spokesperson who said officials were "considering" their next steps after a court injunction blocked the deportation of Florence and Opelo.
They told the newspaper: "Today (Monday 9 April) the court has issued a last minute injunction against the removal of Florence and Opelo Kgari, although their immigration status remains unchanged.
"We have noted the injunction and are carefully considering its implications."
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