The group, which has its headquarters at Llansantffraid, Powys, and stores across Shropshire, achieved revenue of £431.4 million for the year to the end of October compared to £490.6 million a year before.
It said it achieved resilient results in an unprecedented year with an historically poor 2019 autumn planting season and 2020 UK harvest at a 20-year low.
There was subdued farmer confidence and investment, reflecting weaker farmgate prices in the first half of the year and Brexit uncertainty followed by the coronavirus pandemic.
Pre-tax profit was down from £7.55 million in 2018-2019 to £6.98 million although underlying pre-tax profit rose four per cent to £8.37 million.
The proposed final dividend is 10 p, taking the total for the year to 14.6p – a 4.3 per cent rise.
Wynnstay's agriculture division's revenue was down from £358.69 million to £302.58 million and the specialist agricultural merchanting division also fell from £131.84 million to £128.81 million.
The group says that farmer confidence has significantly improved with the EU trade deal and stronger farmgate prices and the UK Agriculture Bill creates significant opportunities with farmers now incentivised for efficiency and environment initiatives.
Trading in the current financial year so far has been in line with management expectations.
Chief executive Gareth Davies said: "Wynnstay's strengths have been clearly demonstrated in what was an exceptionally difficult year for both the agricultural sector and wider society. Our resilient results reflect well on our balanced business model, strong financial management and recent growth initiatives.
"The new financial year has started well, and Wynnstay's performance is in line with management expectations. We remain focused on developing our channels to market, investing to build capacity and capability, particularly advisory, and implementing efficiencies.
"Stronger farmgate prices, the EU settlement and UK Agricultural Bill continue to buoy sentiment across the farming sector. We believe that Wynnstay is in an excellent position to help farmers adapt to new priorities set by the Agricultural Bill, and look to the future with confidence."