“建成投产”常见的英文表达有 “be completed and put into operation/production” 。
例如：
The new factory was completed and put into operation last month.（这家新工厂上个月建成投产了。）
此外，根据不同语境，也有其他类似表达：
“come on stream”： 强调设施、项目等开始正常运行、投入生产。比如：The new power plant will come on stream next year.（这座新发电厂将于明年建成投产。 ）
“go into operation/production”：侧重于表示开始进入运行或生产阶段。例如：The chemical plant went into production after two years of construction.（经过两年的建设，这座化工厂建成投产了。 ）