Yes.
Proficiency isn't tied to anything except your character level (i.e if you multiclass for example Rogue 3 / Cleric 2, your character level is 5, which means your proficiency bonus is +3).
Your proficiency bonus increases everything you're proficient in, full stop. This applies to attacks with weapons you're proficient with, saving throws you're proficient in, skills you're proficient in, etc.
From the Basic Rules, p. 7:
Proficiency Bonus
The table that appears in your class description shows your proficiency bonus, which is +2 for a 1st-level character. Your proficiency bonus applies to many of the numbers you’ll be recording on your character sheet:
- Attack rolls using weapons you’re proficient with
- Attack rolls with spells you cast
- Ability checks using skills you’re proficient in
- Ability checks using tools you’re proficient with
- Saving throws you’re proficient in
- Saving throw DCs for spells you cast (explained in each spellcasting class)