Oct 20 (Reuters) - Investment firm Blackstone Inc (BX.N) would buy a majority stake in Spanx, valuing the shapewear maker at $1.2 billion, the companies said on Wednesday. The deal will allow Spanx to further expand globally and help it strengthen its online business, they added. Spanx founder and Chief Executive Officer Sara Blakely would become the executive chairwoman of Spanx"s newly appointed all-female board of directors. The deal comes months after a report from New York Times said Spanx has tapped Goldman Sachs to explore options including a sale and drawn interest from private equity firms like Carlyle. Rival shapewear label Skims, owned by reality star Kim Kardashian West, said earlier this year it had raised $154 million in funding, reaching a valuation of $1.6 billion as of April. read more Reporting by Deborah Sophia in Bengaluru; Editing by Shailesh Kuber