Li Wei was born in Beijing, China, of Manchu-Chinese parents and was initially trained as an English language teacher at the end of Mao's Cultural Revolution. He worked as an English teacher for two and a half years before studying for a BA in English language and literature at Beijing Normal University. He went to Newcastle University to teach Chinese in 1986. He has an MA in English Language Studies and a PhD in Speech Sciences from Newcastle. His PhD supervisor was the sociolinguist Lesley Milroy with whom he worked on a number of research projects.
He became professor of applied linguistics at Newcastle University in 1998 and was Director of the Centre for Research in Linguistics between 1999 and 2002 and head of the School of Education, Communication and Language Sciences between 2002 and the end of 2006. He joined Birkbeck College in January 2007. In January 2015, he took up the Chair of Applied Linguistics at University College London's Institute of Education.