The average monthly rental income in the area is £697, which is relatively low compared to other areas, but the average property price in the Central Valley is the lowest, averaging just £100,786.
The top ten areas for rental yields are all located in the North, Midlands or Wales.
Profitability is generally lower in England and Wales, where the average rental yield is 4.98 per cent.
Francesca Carlesi, CEO of Molo, explains: From a rental yield point of view, current target regions include the North (where property prices are low and rents are high) as well as commuter towns (where there is a high demand for property).
However, it is also important to consider fast-growing cities or university areas, which will have a stable source of tenants and strong capital investment growth.
Gross rental yields in this area are only slightly lower than in the Central Valley at 7.90%.
However, the average monthly rental income is over £100 lower than the Central Valley at £592 and the average property value is significantly lower at £85,774.
The third highest rental yield was achieved by another region in the North East, South Teesside, which had a gross rental yield of 7.66 per cent. Swansea (with a gross yield of 7.30 per cent) and Coventry (with a gross yield of 7.06 per cent) round out the top five in the UK rental yield rankings.
With a gross rental yield of 3.58 per cent, Camden and the City of London are a third below the national average and are ranked as the locations with the lowest rental yields for rental properties.
Whilst the average monthly rental income here is one of the highest on the list at £2,268, the average property here is also very expensive at £672,104, placing it sixth on the list.
West Essex is another area with low rental yields, with a gross rental yield of 3.64%, meaning it's difficult to make a profit from buy to let properties.
The average monthly rental income is relatively high at £1,800 compared to the national average, but properties in the area are expensive at £548,000.
Dorset (gross yield of 3.67 per cent), Bromley (gross yield of 3.69 per cent) and North Yorkshire (gross yield of 3.70 per cent) are in the top five lowest yields in England and Wales.