Cabinet members approved the proposal which has been debated in public over the past year.
Elland boasts the grade I listed St Mary's Church at the core of the conservation area, dating from the 12th Century.
Council officers say the grand imposing buildings from the early and late Victorian period demonstrate Elland's architectural interest.
The decision will assist the council in deciding planning and other applications, and consent will be required for the demolition of buildings in these areas.
The additional parts of the town now within Elland Conservation Area are: the former Elland Wesley Church, Harold Savage Hall and Bankfield Social Club, Gog Hill, Ellen Royd Clinic and 160-162 Westgate, Brooks, Pendleton, Albion Mills and other buildings off South Lane and James Street.
Head of planning Geoff Willerton said: "The challenge within conservation areas is to manage change in a way that enhances the special character of the area."
Elland was identified in 2009 as a being a conservation area at risk through a national survey carried out by English Heritage.