Rubuta ci gaba don wannan sakin layi - A tserensa na farko, Grand Prix na Ostiraliya, Karthikeyan ya cancanci matsayi na 12. Bayan mummunan farawa wanda ya gan shi ya sauka zuwa matsayi na 18 a ƙarshen zagaye na farko, ya gama a 15th, zagaye biyu a bayan mai nasara Giancarlo Fisichella. Ya sami maki na farko a gasar Grand Prix ta Amurka ta 2005 inda dukkanin kungiyoyi uku sai uku suka janye saboda jayayya game da lafiyar taya. Ya gama na huɗu, ya gama a gaban direbobin Minardi biyu amma a bayan abokin aikinsa Monteiro. Baya ga USGP, mafi girmansa shi ne matsayi na 11. A cikin gwajin kyauta na Grand Prix na Japan na 2005, ya kasance mafi sauri na dogon lokaci kuma a ƙarshe ya cancanci 11th. A Babban Gasar Ciniki ta 2005
ya cancanci a matsayi na 15. A cikin rashin sa'a a ƙarshen kakar sa ta 2005, Karthikeyan ya yi karo da Jordan a cikin bango a tseren China, amma ba shi da rauni kuma ya sami damar ba da hira bayan haka.