PKF in Birmingham has won a contract to audit Laird, the global electronics and security systems group employing more than 8,000 people in North America, Europe and Asia.
The accountancy firm already handled the company's UK operations but will now take on its US interests.
Partner Robert Hudson, who leads the PKF team, said: "To win the work against prestigious competition was very gratifying, but it shows that in Birmingham we have the scope and range to service international assignments.
"We will be working with our colleagues in PKF offices throughout the US but the work will be led and coordinated from Birmingham."
Simon Murphy, chief executive of Birmingham Forward which runs the Advised in Birmingham marketing initiative, said: "This is another excellent example of a significant business being advised in Birmingham."