The third seed, who is playing in her first Games and carried Russia's flag at the Opening Ceremony, continued her fine form on the Wimbledon grass this week to win 6-2 6-3.
Sharapova has served particularly well and she overpowered Kirilenko in the first set in particular.
The 14th seed, a quarter-finalist at Wimbledon last month, hit back in the second set and was a break ahead at 3-2, but Sharapova responded with a run of four games in a row, putting away a forehand on her second match point.
In the final Sharapova will face Wimbledon champion Serena Williams, who continued her romp through the draw with a 6-1 6-2 win over world number one Victoria Azarenka.
They had met in the semi-finals of Wimbledon last month, where Azarenka gave a good account of herself despite losing in straight sets, but today she simply could not live with the power of Williams.
The USA player and Sharapova will now face each other not just for a gold medal but also to become only the second woman after Steffi Graf to win all four grand slams and the Olympic title in their career.