Convert string to Time

string Time = "16:23:01";
DateTime date = DateTime.Parse(Time, System.Globalization.CultureInfo.CurrentCulture);

string t = date.ToString("HH:mm:ss tt");

This gives you the needed results:

string time = "16:23:01";
var result = Convert.ToDateTime(time);
string test = result.ToString("hh:mm:ss tt", CultureInfo.CurrentCulture);
//This gives you "04:23:01 PM"  string

You could also use CultureInfo.CreateSpecificCulture("en-US") as not all cultures will display AM/PM.

"16:23:01" doesn't match the pattern of "hh:mm:ss tt" - it doesn't have an am/pm designator, and 16 clearly isn't in a 12-hour clock. You're specifying that format in the parsing part, so you need to match the format of the existing data. You want:

DateTime dateTime = DateTime.ParseExact(time, "HH:mm:ss",
                                        CultureInfo.InvariantCulture);

(Note the invariant culture, not the current culture - assuming your input genuinely always uses colons.)

If you want to format it to hh:mm:ss tt, then you need to put that part in the ToString call:

lblClock.Text = date.ToString("hh:mm:ss tt", CultureInfo.CurrentCulture);

Or better yet (IMO) use "whatever the long time pattern is for the culture":

lblClock.Text = date.ToString("T", CultureInfo.CurrentCulture);

Also note that hh is unusual; typically you don't want to 0-left-pad the number for numbers less than 10.

(Also consider using my Noda Time API, which has a LocalTime type - a more appropriate match for just a "time of day".)