Reeves told MPs she was raising taxes by £40bn, with more than half of that sum coming from businesses.
From April, firms will pay National Insurance at 15% on salaries above £5,000, up from 13.8% on salaries above £9,100.
That will raise an additional £25bn a year.
However employment allowance – which allows smaller companies to reduce their NI liability – will increase from £5,000 to £10,500.
Conservative Senedd leader Andrew RT Davies accused the chancellor of presenting a “smash and grab Budget” that “will have a devastating impact in Wales”.
“This Budget is built on the back of keeping pensioners cold this winter, and the National Insurance rise will be an incredibly destructive jobs tax for Wales’ economy which is already struggling after decades of Labour rule,” he said.
Ben Lake, who speaks for Plaid Cymru on Treasury matters at Westminster, said: “Regrettably, the Budget falls short of the transformative change that was promised during the general election.
“Labour promised two governments working together, but it appears the Welsh government was sidelined yet again by the UK government, as there is little good news for Wales,” he added.
The Welsh Liberal Democrats said the Budget failed to offer an ambitious vision for Wales that would mark a long-term investment in its future.
“It punishes small businesses and will be a disaster for family farms,” they added.
