According to figures, published in the quarterly ratings guide by Hemscott, the firm increased its total number of clients by three during the last three-month period.
The broker now has a total of 244 clients, which is more than twice as many as the second-placed firm Numis Securities.
Figures from the guide revealed that the latter had a total of 118 clients after it gained five new clients during the quarter.
JPMorgan Cazenove also worked with the largest clients, with the Financial Times reporting that 35 of the firms it advised currently listed in the FTSE 100.
Bank of America Merrill Lynch came second in this section of the rankings, after working with 33 FTSE listed firms.
Further findings from Hemscott showed that JPMorgan Cazenove also has the most clients in its capacity as a financial advisor with 93.
Seymour Price was second in this section of the quarterly ratings.
JPMorgan Cazenove became a wholly owned part of JPMorgan in November 2009.
By Jim Ottewill