Vanocur then worked on the city staff of The New York Times for two years, leaving in 1957 to join NBC News. He held various positions, including White House correspondent, National Political correspondent, Washington correspondent for the Today Show, contributing editor to the Huntley-Brinkley Report, and host of First Tuesday, a monthly magazine program.

From 1975 to 1977, Vanocur was television editor and critic at The Washington Post.

Vanocur held positions at ABC News from 1977 to 1992. These positions included Chief Diplomatic correspondent, Senior correspondent in Buenos Aires during the Falkland Islands War in 1982, and was anchor of Business World, the first regularly scheduled business program on television. He also covered the 1987, 1988 and 1989 Economic Summit meetings and was ABC News Chief overview correspondent during the 1980 and 1984 presidential elections.

From 1995 to 2002, Vanocur was anchor of two programs at the History Channel, Movies in Time and History's Business.

Before joining the History Channel, Vanocur was a visiting scholar at the Freedom Forum First Amendment Center at Vanderbilt University in Nashville. He was also co-host of Vanderbilt's Freedom Speaks, a weekly series produced by the Center and aired on PBS.

Vanocur attended Northwestern University where he majored in political science and was a graduate student at the London School of Economics.

He now lives in Santa Barbara, California, where he heads his company, Old Owl Communications, a full-service communications and consulting corporation.