The two companies will help the consortium develop the next version of the software, which is due later this year, said UnitedLinux general manager Paula Hunter.
"[They] will participate in joint marketing programs and have access to special support and technology programs," Hunter said.
UnitedLinux 1.0 has already been certified for both IBM and AMD's products, including IBM's eServers and AMD's forthcoming 64-bit Opteron processors.
While UnitedLinux works with many companies, IBM and AMD represent "the most comprehensive business relationship with players outside of the UnitedLinux founders", claimed Hunter.
IBM and AMD last week agreed to work together on developing future process technologies for chip manufacturing.
UnitedLinux is an industry consortium made up of Linux vendors Conectiva, The SCO Group, SuSE Linux and Turbolinux. At Comdex in November, it released a Linux version for enterprise servers called UnitedLinux 1.0 to which each company has added its own set of features.