Sulkiewicz was born in Skirsobole Tatarskie, Congress Poland (now part of Lithuania) to a Tatar family with a tradition of support for the cause of Polish independence.

In Vilnius, then part of Poland, Sulkiewicz was introduced into socialist circles and became an active member of the Social-Revolutionary Party Proletariat.

[5] With Józef Piłsudski, Stanisław Wojciechowski, Stefan Bielak and Ludwik Zajkowski, he took part in a meeting in a forest near Vilnius that was later recognized as the First Congress of the PPS.

[8] Partly because Russian officials did not expect a Muslim like Sulkiewicz to be involved in Polish independence campaigns, he was able to continue his clandestine conspiratorial activities for an extended period without being detected.

He left his customs job in 1900 and, on party orders, moved to Łódź, where he set up a printing shop for the Robotnik newspaper.

After the creation of Polish National Organization, he became its director in the Vilnius region and traveled on diplomatic missions to Berlin, Copenhagen, Sweden and Kiev.

He then went to Galicia and, from there, was sent by Piłsudski to German-controlled Warsaw, where he was active in the Polish Military Organisation (Polska Organizacja Wojskowa) and the PPS.