The 10-year contract covers the whole of Phase One construction, which is due to start next year. The London to Birmingham stretch of rail will require a wide range of infrastructure work including the planting of around two million trees.
The three companies will focus on providing engineering and construction management support as well as helping procure the main civils contracts for the London to Birmingham stage of the route.
CH2M and Atkins are involved in London's Crossrail project, and SENER was recently involved in Spain's high speed rail network.
HS2's managing director of construction, Jim Crawford, said: "Today's contract award marks an important milestone as we continue to move towards the start of construction in 2017.
"It is vital that we constantly challenge our suppliers to ensure we deliver long-term value for money for the taxpayer as well as a world-class railway for all our passengers, stakeholders and communities along the line."
Although millions of trees will be required for the project, nurseries are still in the dark about the specifics of the tree procurement strategy and landscaping works. The industry has repeatedly raised concerns about the short lead-in time for the project, which could leave nurseries struggling to supply the trees from within the UK.
Architecture tenders are due to be published next month, HS2 Design Panel chair Sadie Morgan told an audience at last week's EcoBuild exhibition in London. She suggested contractors should pair up with architects if they wanted to bid for any of the works.