The team will be lead by Giro d'Italia winner Vincenzo Nibali, with sponsorship from Bahrain and bike brand Merida.
Siutsou turned professional with Nibali at the Fassa Bortolo team after winning the under-23 world title in Verona in 2004. The 34-year-old Belarus rider spent four season with Team Sky but joined Dimension Data for 2016 and finished tenth overall in the Giro d'Italia.
"I'm really proud to join Bahrain Merida Pro Cycling Team, because I can put my experience to support a champion like Vincenzo Nibali. I'm looking forward to help him during his next challenges as well as to support the captains appointed from time to time. I believe this team will get soon a lot of satisfactions,” Siutsou said when the announcement was made.
Siutsou is the current Belarus road race and time trial national champion and his ridden 15 Grand Tours during his 12-year career.
The 36-year-old Božič also brings experience to the Bahrain Merida team. He is currently riding for Cofidis after four seasons at Astana and three with Vacansoleil. The Slovenian finished second in Gent-Wevelgem in 2013, with stage victories at the Vuelta a Espana, Tour of Britain and Tour de Suisse on his palmares.
"I decided to be a part of the new team because after many years in the pro cycling I will be a part of the new established team which is been formed and coming together nicely," he said.
"The fact that I know many people already from the team and that I fully trust them is another reason I decided to join. I can hardly wait for the new season and I am really happy that I am still able to compete on the top level and I'm sure that the team will have a program which will suit me and there needs. My main task in the team is that I help younger cyclists with my experiences which I've got in all those many years being a part of the pro cycling world."
The Bahrain Merida team has already announced the signing of Nibali, Manuele Boaro and Giovanni Visconti and confirmed that several members of Nibali's entourage at Astana will also be part of the team, including coach Paolo Slongo and personal soigneur Michele Pallini.
Other signings are expected to be revealed shortly as the team prepares to apply for a WorldTour licence. Former Lampre-Merida manager Brent Copeland is working to complete the team's roster.
"For our team the signing of Kanstantin and Borut is very important step as they contribute hugely in helping build the foundations and the base of the team," he said.
"With these two very experienced riders we are that much more confident when going into the races, they are riders that can cover many roles on the road which in today's cycling world is always more important. We're very excited to see them racing in our exciting new team."