Sudha Murthy says it was a "pleasant surprise" to be appointed to the upper house for a six-year term.
Chancellor Rishi Sunak and his wife make the Sunday Times Rich List for first time with £730m fortune.
Akshata Murty has previously not paid UK tax on shares worth £700m in an Indian tech company.
Akshata Murty is charged yearly fee for status allowing her not to pay UK tax on overseas earnings.
Rishi Sunak has been under pressure over his wife's stake in Infosys, which operates in Russia.
The chancellor speaks out over criticism of his wife, who owns shares in a firm operating in Russia.
The chancellor's wife has a stake in an Indian multinational that has kept its office in Moscow.
An Indian software giant part-owned by the chancellor's wife has kept its presence in Moscow.
