In the three-month period to June, net profit reached 166.2 billion pesos ($40.6 million).
Meanwhile, the conglomerate saw interest income soar 70% to 7.15 trillion pesos in the April-to-June period.
The company said results were "negatively impacted by a 10.1% appreciation of the Colombian peso."
It added that the drop in profit was also due to lower margins.
"Our banking subsidiaries continue to experience challenges on their intermediation margins as a result of the rapid increase in the cost of funds," the company said in a statement.
The financial portfolio of Grupo Aval includes Colombian banks Banco de Bogota, Banco Popular, Banco AV Villas and Banco de Occidente.
($1 = 4,096.08 Colombian pesos)
(Reporting by Noe Torres in Mexico City, Writing by Isabel Woodford)
