Bayan kammala karatunta a shekarar 1979, Rometty ta tafi aiki a Cibiyar General Motors a Detroit, inda ta ke da alhakin ci gaban aikace-aikace da tsarin. A shekarar 1981 ta shiga IBM a matsayin mai nazarin tsarin da injiniyan tsarin a Detroit. Da farko tana aiki tare da abokan ciniki a masana'antar inshora, ta shafe shekaru goma na farko a IBM a matsayin fasaha. The New York Times ya rubuta cewa ta "da sauri ta koma zuwa jerin ayyukan gudanarwa", inda ta yi aiki tare da abokan ciniki a cikin inshora, banki, sadarwa, masana'antu da kiwon lafiya. Ta shafe shekarun 1990 tana aiki a tallace-tallace, kuma a ƙarshen shekarun 1990 tana taimaka wa abokan ciniki kamar Prudential Financial, Inc. tare da fasalin intanet ɗin su. Ta shiga Kungiyar Shawara ta IBM a 1991. Tambaya: Yaushe ta shiga IBM?
Shekara ta 1991