The 12 titles are free and paid-for newspapers in North London, East London and Essex with a total weekly circulation of just over 316,000.
The papers include the paid-for titles the Islington Gazette and Hornsey Journal, and the Herald free series.
In East London, the deal includes the paid-for East London Advertiser and Hackney Gazette and the three free Express newspapers covering Stratford, Stoke Newington, Shoreditch and the surrounding area.
In Essex, the acquisition includes four newspapers in the Barking and Dagenham Post paid-for series and three free newspapers covering the Barking, Illford and Romford areas.
John Fry, chief executive of Archant, said: "Opportunities to acquire regional newspaper portfolios of quality and scale are few and far between. We therefore consider this acquisition to be of significant strategic importance given the geographic proximity to our existing areas of publication and the enhancement it gives to our coverage in and around North and East London."
This acquisition sees Archant, which owns four daily regional newspapers including the Eastern Daily Press and the East Anglian Daily Times, consolidate its position as a UK top 10 regional newspaper publisher.
The company, which owns more than 50 weekly newspapers and around 60 magazines, is the largest privately owned UK local and regional newspaper group.
If you have an opinion on this or any other issue raised on Brand Republic, join the debate in the .