50-year-old Shah, the closest and controversial aide of Modi, was unanimously appointed to the top post in BJP at a brief business-like meeting of its Parliamentary Board, the party's highest decision-making forum, where incumbent Rajnath Singh resigned after 18 months at the helm.
The former Minister of State for Home in Gujarat, who faces charges in the Sohrabuddin Sheikh fake encounter killing case, is largely credited with BJP's stunning performance in UP where it got 71 of the 80 Lok Sabha seats.
The meeting was attended among others by Modi, senior leaders L K Advani, Murli Manohar Joshi, M Venkaiah Naidu, Nitin Gadkari and Sushma Swaraj.
Finance Minister Arun Jaitley, who had to table the pre-Budget Economic Survey in Lok Sabha, joined the press conference where the announcement of Shah as BJP chief was made by Singh before all these leaders.
"From now on, Amit Shah will be the president of BJP and will lead the party. His appointment was approved unanimously," Singh said flanked by Modi and other leaders.
Shortly after the announcement, Modi and Singh offered sweets to Shah while other leaders including Advani, Joshi, Swaraj and Jaitley gave him bouquets. Singh also garlanded Shah.
As reporters started asking questions, Shah replied "I will speak later" bringing the brief ceremony to a close.
Asked about both Modi and Shah hailing from Gujarat being put in charge of the government and the party, Singh said in a big party like BJP decisions like this cannot be viewed from the prism of region, religion and caste.