The scheme - now called Pentre Awel – has been approved by the Swansea Bay City Deal’s Joint Committee.
This follows the project’s approval by Carmarthenshire County Council’s Executive Board and unanimous sign-off at Full Council.
Proposed for an 83-acre site at Delta Lakes on Llanelli’s coastline, Pentre Awel will be the first development of its scope and size in Wales.
Pentre Awel will provide public, academic, business and health facilities all on one site to boost employment, education, leisure provision, health research and delivery, and skills and training.
The project is planned to include integrated care and physical rehabilitation facilities to enable the testing and piloting of life science technologies aimed at enhancing independent and assisted living.
The council-run leisure centre element of the project will feature a cutting-edge gym, a 25-metre swimming pool, a learner pool and an indoor play area.
Worth millions of pounds to the local economy, Pentre Awel will also create a wide range of employment opportunities across the Swansea Bay City Region as whole.
Pentre Awel is being delivered by Carmarthenshire County Council in partnership with Hywel Dda University Health Board, Universities and Colleges.
The council is working with community partners to ensure the project accommodates the work, health and care needs identified and prioritised by local residents through extensive consultation.
Pentre Awel is due to be part-funded by the £1.3 billion Swansea Bay City Deal, with a total of £40 million being sought for the project.
Following approval at Joint Committee, the project’s business case will now be submitted to the UK Government and Welsh Government for final sign-off.
Cllr Emlyn Dole, Carmarthenshire County Council Leader, said: "Pentre Awel is an exciting landmark project – not just for Llanelli and Carmarthenshire, but for the Swansea Bay City Region as a whole because of the high-quality job opportunities and economic boost it will generate, helping attract even more future investment.
"With world-class leisure, business, assisted living and health facilities on one site, it’s a project that will deliver for local people, while putting Llanelli and Carmarthenshire on the map as a global example of best practice for life science and well-being excellence.
"The importance and relevance of this project has been further reinforced through the Covid-19 emergency. It will help address skills shortages in health and care, while also capitalising on digital advances in delivering healthcare at home or in the community.
"We are totally committed to delivering this project, which will now be submitted to the UK Government and Welsh Government for final sign-off following its approval at Joint Committee."
The Pentre Awel project will also include a skills centre focusing on health and care training, along with a clinical delivery centre to deliver multi-disciplinary care closer to home.
Assisted living accommodation will also feature, along with a nursing home, a hotel, expansion space for businesses, and elements of both open market and social and affordable housing. Landscaped outdoor spaces for recreation on site will benefit from spectacular views across the Loughor Estuary and Carmarthen Bay.
Funded by the UK Government, the Welsh Government, the public sector and the private sector, the Swansea Bay City Deal is being led by Carmarthenshire County Council, Neath Port Talbot Council, Pembrokeshire Council and Swansea Council, in partnership with Swansea University, the University of Wales Trinity Saint David, Swansea Bay University Health Board and Hywel Dda University Health Board.