The global firm announced that its overall revenue fell to £505 million in the 12 months to 30 April 2016, down from £533 million in the corresponding period last year.
Average profit per equity partner also decreased to £603,000 from £716,000 the year prior.
“Our results last year are not what I wanted them to be,” said Paul Jenkins, managing partner of Ashurst.
“2016 remained a period of change at Ashurst following the implementation of our strategy, with the firm making significant investment in order to drive greater efficiency and innovation.
“Although this will greatly benefit our business and client service, inevitably it has impacted the bottom line.”
Last month Ashurst announced a new global management structure for the firm, including a head of innovation role and a head of clients role. The firm also made a number of appointments to the three global divisions of its executive team.
To explain Ashurst’s poorer performance, Mr Jenkins pointed to weak global economic conditions that proved “more challenging than we anticipated”.
“The global slowdown in the oil and gas and the mining sectors, to which we have considerable exposure, had a notable impact, as did ongoing geopolitical uncertainty and a slowdown in China,” he said.
“A weakening against sterling of key currencies that are a significant part of our business also had a significant effect, with the negative impact of forex reducing revenue by 5 per cent.”
However, Mr Jenkins noted that Ashurst delivered significant growth in Asia and Europe over the 12 months, most notably in Hong Kong and Paris.
“We have increased revenue in most of the financial services sectors within which we operate, notably funds,” he added.
“The built environment sector has also performed well.”
Mr Jenkins said Ashurst will continue to actively invest in the business over the next 12 months by making a number of strong internal promotions and hires that will play a key role in driving the firm forward.
“I am confident that the new leadership team and a continued focus on clients, efficiency and innovation will deliver a stronger performance in FY17,” he said.
By comparison, other firms have posted increases to revenue in the same period.
Allen & Overy posted a 2.3 per cent rise in revenue to £1.31 billion from the year before.
However, a slightly lower profit before tax than last year was recorded, with £562 million for the period 1 May 2015 to 30 April 2016.
The average profit per Allen & Overy equity partner remained stable at £1.2 million.
The global firm’s financial year results revealed a 7 per cent rise in revenue, from £815 million last financial year to £870 million this financial year.
Profit was recorded at £278.2 million, also up 7 per cent on the previous financial year, and up 20 per cent over two years.
Meanwhile, Clyde & Co recorded revenue growth of 13.2 per cent to £447.3 million in the year ending 30 April 2016, according to pre-audit figures.
Its average profit per equity partner reached a new high of £665,000.