The rebranding assignment will include all above-the-line, below-the-line and digital creative work.
The charity is seeking to draw up a long list of shops using an external consultant ahead of final selection. It is seeking agencies with previous experience of working in the charity sector.
Recent work has been by WWAV Rapp Collins West.
"We have got a rebranding exercise going on and it will, no doubt, involve getting in a number of agencies, but no details have been confirmed," a Shelter spokeswoman said.
The move comes as the number of homelessness charities rises.
In November last year, TBWA/London launched the Big Issue Foundation's first campaign in two years, using press executions to highlight the plight of the homeless.
The six executions aimed to get the public to "think bigger" and confront their prejudices about homeless people and ran in titles including GQ, Loaded, Dazed & Confused and Flux.
The campaign formed part of a wider Big Issue initiative called "lethal streets" that will include a cinema campaign.
In August, the rival charity Crisis rebranded with a rejuvenated image that saw the scrapping of its red house icon in favour of an image of a pane of glass and the word "help" written across it.
Shelter operates a network of 50 housing aid centres, projects and surgeries, a 24-hour phone service called Shelterline, as well as training courses and campaigns to raise awareness of the problem.
Shelter's aim is for everyone in the UK to have a decent home, and to improve the lives of the homeless and badly housed people.