Work starts at the end of May on the vital rail artery, following years of detailed designs and collaborations between leading marine, coastal and railway engineering experts.
BAM Nuttall will increase the sea wall height by 2.5m and include wave returns to reduce the impact of waves and the likelihood of the line being closed during adverse weather.
The local community will also benefit from improvements to the promenade, keeping clear views of the coast.
The upgrade is expected to take nine months to complete, with work halting during the peak summer season to minimise disruption on tourism.
David Lovell, Network Rail senior programme manager for the Dawlish sea wall project, said: “Our plans have been drawn up by world leading engineers and it will provide greater protection to the railway and town from rising sea levels and extreme weather.”
Huw Jones, Rail Divisional Director at BAM Nuttall, said: “We have a long association working at Dawlish, and successfully delivered emergency recovery of the railway during 2014.
“We look forward to continuing our close collaboration with local stakeholders, Network Rail, and our supply chain partners. This is a great opportunity to demonstrate our commitment to creating sustainable solutions that enhance the lives of passengers and everyone in communities where we work.”