Fortis Homes said the development would provide a financially-viable way to save the historic building.
Managing director Doug Innes said: “We have engaged openly and positively with the community and elected members throughout the last nine months, and we have changed the proposals, where possible, in response to what we heard.
“We’ve been encouraged by the level of local engagement and a general sense that the community welcomes the opportunity to see a long-neglected site generated and Gattonside House safeguarded.
“We now hope for a proactive and timely determination so work on Gattonside House can start to halt the deterioration.
“We look forward to working with Scottish Borders Council as it considers the application.”