The cash will be used to spruce up its fixtures for beers, wines and spirits and fresh produce, as well as a new "food to go" feature, with more than 100 stores to be refurbished in 2017.
Chief executive Matthew Barnes said the move was the result of a "listening exercise" involving more than 50,000 shoppers.
The German-owned firm added that it will open 70 new stores in the UK next year as part of plans to increase supermarket numbers from 659 to 1,000 by 2022.
Sales grew by 12% to £7.7bn in 2015, with Aldi doubling its turnover in just three years.
Operating profits dipped 1.8% to £255.6m, which the firm put down to its "continued investment in prices."
Aldi said its future capital expenditure plans are "unaffected" by the UK's decision to quit the EU, pledging to make "substantial investments", including enlarging two existing distribution sites, redeveloping its UK head office in Atherstone, Warwickshire, and opening a new distribution centre in Cardiff next year.
Barnes said: "During the past five years we have invested close to £1.7bn in the UK by opening more stores than any other supermarket and enhancing our distribution capabilities.
"Our future capital expenditure plans are unchanged - we will continue to make significant investments in our business, paying our employees more than any other supermarket."
Aldi said 761,000 new customers walked through its doors last year, helping its market share grow to a record high of 6.2%.
Barnes said the firm would continue to invest in prices in order to maintain a "significant price advantage" over rivals.
"Regardless of what competitors may say or do, our price advantage will be maintained and our customers will always pay the lowest grocery prices in the UK," he said.
Aldi said its strongest-performing categories last year included fresh meat and fish and its Exquisite wine range, while sales of its Mamia nappies grew by 29%, making it the UK's second biggest-selling brand.
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