He represented Vancouver City in the Legislative Assembly of British Columbia from 1900 to 1909 as a Conservative. After completing his schooling, Tatlow came to Montreal where he was hired by the Montreal Ocean Steamship Company and later a brokerage office. He joined the militia and came to Victoria in 1879 to inspect the coastal defences there.
Tatlow remained there as instructor to the local militia and custodian for artillery supplies.
The following year, he was hired as private secretary to the lieutenant governor, Albert Norton Richards. He continued in the same function for Richards" successor, Clement Francis Cornwall.
Tatlow resigned that post in 1886 and moved to Vancouver where he was a real estate, insurance and mining broker. Tatlow ran unsuccessfully for a seat in the provincial assembly in 1890 and 1894 before being elected in 1900.
He introduced a private member"s bill requiring all immigrants to be able to write in a European language.
Tatlow served in the provincial cabinet as Minister of Finance and Agriculture and as Commissioner of Lands and Works. He also served as deputy premier. He resigned his seat in October 1909 after Richard McBride proposed guarantees to help finance the construction of the Canadian Northern Railway.
Tatlow died in Victoria at the age of 54 after being ejected from his carriage.
Mount Tatlow was named in his honour.
He was a member of the city"s park committee from 1888 to 1905 and served as chairman from 1895 to 1903.