Action for Children has already begun introducing the technology to its fostering services in England and some residential services in Wales.
The Mind of My Own app aims to encourage children to share their thoughts and feelings more regularly, and to avoid difficult face-to-face conversations during visits.
They can send messages or emojis at any time, which go to a central administrator at Action for Children, who assigns the statement to the appropriate social worker.
Children as young as three have used the app, which can be installed on phones or other portable devices.
The charity adopted the technology following a pilot with Bolton Children's Rights Services in 2018.
The results showed children used the app as an alternative way to not only vocalise problems but also celebrate good moments in their lives.
One young person said: "It's brilliant as it helps you say the things that you want to say without being afraid.
"I can tell people what I want and when, so it helps them to understand my point view and what's really going on in my life."
In one case that was not part of the Action for Children pilot, a child chose to reveal that they were being sexually abused through the app rather than face-to-face.
The application also records and stores what the child has said, meaning social workers do not have to write up conversations.
For example, prior to a social worker visit or at any time they are experiencing a difficult emotion, a child can select from a series of emoticons to describe how they are feeling, such as anxious, angry or hopeful.
Action for Children national director John Egan acknowledged there was a concern about confidentiality with using digital applications, but said the technology was secure.
"Feedback so far has been hugely positive and our staff are finding the communication invaluable," he said.
"Children who have sometimes struggled to discuss difficult issues are now using the app to start a conversation.
"The apps will complement, not replace, our face-to-face work."
He added that the organisation planned to use data collected by the app to track themes and issues that would help them develop and adapt services.
British Association of Social Workers professional officer Gavin Moorghen said while the use of new technologies that help social workers build relationships was to be encouraged, nothing could replace direct contact between social workers and children.
"Direct relationship-based work is the best model of practice to achieve better outcomes for children," he said.
"This is why BASW England's current 80:20 Campaign is working to free social workers from excessive admin and red tape, so they can have more direct contact with children and families.
"Yet we live in a digital age, and our members tell us they find it limiting if they cannot use technology, including social media, to engage and communicate with children."
In 2016, East Sussex County Council revealed it was using the Mind of My Own app to gather the views of looked-after children in preparation for, and during, meetings about care plans.
Mind of My Own won the 2017 CYP Now Children in Care Award, as well as winning awards in the previous three years.