The cotton mealybug Phenacoccus solenopsis Tinsley is an emerging invasive insect pest. Since its first report as a pest in the United States in 1991, it has invaded and colonized more than 23 countries over the past century. It was first recorded from Pakistan in 2006 and from China in 2008. In this study, we performed field surveys from 2010 to 2012 and obtained mtCOI sequences from specimens across China and Pakistan, then compared them with already available mtCOI sequences from additional Asian and North American countries. Our genetic analysis provides evidence that P. solenopsis should be classified into two groups, one of which is found only in the United States, and the other found only in Asia. The Asian group contains nine unique haplotypes, two of which have invaded and spread across China, Pakistan, India, and Vietnam over the last 4–6 yr. Our genetic analysis also indicates that P. solenopsis has a close relationship with the parasitoid wasp Aenasius bambawalei Hayat, providing preliminary evidence of a congruent spread of this mealybug and its parasitoids across China.