Laschet, who went to vote alongside his wife Susanne Laschet, posed for media on Sunday (September 26) while voting - yet the 'x' marks on his ballot were clearly visible in the boxes next to the CDU.
This year's German national election was been deemed too close to call.
The centre-left Social Democrats (SPD) have been mounting a strong challenge to retiring Chancellor Angela Merkel's conservatives.
Laschet's promise of "steadfastness" has not been resonating with voters worried about climate change, immigration and the COVID-19 pandemic. The conservatives trailed the Social Democrats in the latest opinion polls despite narrowing the gap.
Laschet's ratings have also suffered since he was caught on camera laughing during a visit to a flood-hit town in his home state of North-Rhine Westphalia in July.